Evolution of the histologic classification of thyroid neoplasms and its impact on clinical management.

The vast majority of low grade follicular cell derived thyroid carcinomas follows an indolent clinical course and is associated with very low mortality. Risk stratification using multiple clinical and pathologic characteristics has become the standard of care to guide appropriate management and avoid overtreatment. Over the past few decades, the field of thyroid pathology has witnessed several major changes that significantly impacted upon patients' care. These are: 1) The reclassification of non-invasive encapsulated follicular variant of papillary thyroid carcinoma as noninvasive follicular thyroid neoplasm with papillary-like nuclear features; 2) the diagnosis of Hurthle cell carcinoma based on the presence of capsular and vascular invasion; 3) a detailed definition of poorly differentiated thyroid carcinoma, taking into consideration mitosis and necrosis; and 4) the emphasis on a detailed pathologic analysis such as the extent of vascular invasion and extrathyroidal extension. This review describes these histological concepts and details the history, rationale, and clinical impacts of such changes. These shifts in the classification and characterization of thyroid carcinoma provided a platform supporting therapy de-escalation. In addition several lessons were learned from these changes especially from the misclassification of the non-invasive encapsulated follicular variant of papillary thyroid carcinoma. We hope that the lessons learned will help better classify tumors in the future whether arising in the thyroid or other organs.

What hides behind the MASC: clinical response and acquired resistance to entrectinib after ETV6-NTRK3 identification in a mammary analogue secretory carcinoma (MASC).

BACKGROUND: Mammary analogue secretory carcinoma (MASC) is a recently described pathologic entity. We report the case of a patient with an initial diagnosis of salivary acinic cell carcinoma later reclassified as MASC after next-generation sequencing revealed an ETV6-NTRK3 fusion. PATIENTS AND METHODS: This alteration was targeted with the pan-Trk inhibitor entrectinib (Ignyta), which possesses potent in vitro activity against cell lines containing various NTRK1/2/3 fusions. RESULTS: A dramatic and durable response was achieved with entrectinib in this patient, followed by acquired resistance that correlated with the appearance of a novel NTRK3 G623R mutation. Structural modeling predicts that this alteration sterically interferes with drug binding, correlating to decreased sensitivity to drug inhibition observed in cell-based assays. CONCLUSIONS: This first report of clinical activity with TrkC inhibition and the development of acquired resistance in an NTRK3-rearranged cancer emphasize the utility of comprehensive molecular profiling and targeted therapy for rare malignancies (NCT02097810).

Outcomes in patients with poorly differentiated thyroid carcinoma.

BACKGROUND: Poorly differentiated thyroid cancer (PDTC) accounts for only 1-15% of all thyroid cancers. Our objective is to report outcomes in a large series of patients with PDTC treated at a single tertiary care cancer center. METHODS: A total of 91 patients with primary PDTC were treated by initial surgery with or without adjuvant therapy at Memorial Sloan-Kettering Cancer Center from 1986 to 2009. Outcomes were calculated by the Kaplan-Meier method. Clinicopathological characteristics were compared for PDTC patients who died of disease to those who did not by the χ(2) test. Factors predictive of disease-specific survival (DSS) were calculated by univariate and multivariate analysis using the log rank and Cox proportional hazards method, respectively. RESULTS: With a median follow-up of 50 months, the 5-year overall survival and DSS were 62 and 66%, respectively. The 5-year locoregional and distant control were 81 and 59%, respectively. Of 27 disease-specific deaths, 23 (85%) were due to distant disease. Age ≥ 45 years, pathological tumor size >4 cm, extrathyroidal extension, higher pathological T stage, positive margins, and distant metastases (M1) were predictive of worse DSS on univariate analysis. Multivariate analysis showed that only pT4a stage and M1 were independent predictors of worse DSS. CONCLUSIONS: With appropriate surgery and adjuvant therapy, excellent locoregional control can be achieved in PDTC. Disease-specific deaths occurred due to distant metastases and rarely due to uncontrolled locoregional recurrence in this series.

Clinical outcomes and molecular profile of differentiated thyroid cancers with radioiodine-avid distant metastases.

BACKGROUND: Radioiodine (RAI) remains the mainstay of therapy for RAI-avid (RAIA) distant metastatic thyroid carcinoma. We previously demonstrated that RAI-refractory distant metastatic thyroid cancers commonly harbor BRAF mutations. However, the molecular profile of RAIA metastatic thyroid cancer is unknown. Here we describe the mutational profile of thyroid tumors from follicular cell-derived cancer (FCDTC) patients presenting with RAIA distant metastases. In addition, we aimed to correlate clinical outcomes of RAI therapy with clinicopathological factors and tumor mutational status. METHODS: We retrospectively identified 43 patients with FCDTC who had RAI uptake in the lungs and/or bones on their initial ¹³¹I postablation scan. Primary tumors were genotyped for known mutations in thyroid cancer genes. Structural response to RAI was assessed 6-18 months after each administered RAI activity and at the end of follow-up. RESULTS: RAS, BRAF, RET/PTC, and PIK3CA mutations were found in 42, 23, 10, and 2% of tumors, respectively, and the remaining 23% were wild type. None of these patients achieved cure after repeat RAI therapies, and most patients (54%) experienced disease progression despite repeated RAI administration. There was an increased prevalence of RAS mutations in these RAIA tumors. RAS-mutant cancers were more likely to concentrate iodine on diagnostic whole body scans. Despite this, structural response to RAI was not influenced by tumor genotype. CONCLUSIONS: RAIA metastatic FCDTC are overrepresented with RAS mutations, whereas RAI refractory metastatic thyroid cancers are enriched with BRAF mutations. Despite a seemingly preserved ability to concentrate iodine, RAI therapy is ineffective in achieving cure in most patients with RAIA metastatic FCDTC, even in RAS-mutant disease. These poor outcomes may be improved based on recent evidence that pretreatment with MAPK kinase 1/2 inhibitors enhances responses to RAI, particularly in patients with RAS-mutant tumors.

Progression of BRAF-induced thyroid cancer is associated with epithelial-mesenchymal transition requiring concomitant MAP kinase and TGFß signaling.

Mice with thyroid-specific expression of oncogenic BRAF (Tg-Braf) develop papillary thyroid cancers (PTCs) that are locally invasive and have well-defined foci of poorly differentiated thyroid carcinoma (PDTC). To investigate the PTC-PDTC progression, we performed a microarray analysis using RNA from paired samples of PDTC and PTC collected from the same animals by laser capture microdissection. Analysis of eight paired samples revealed a profound deregulation of genes involved in cell adhesion and intracellular junctions, with changes consistent with an epithelial-mesenchymal transition (EMT). This was confirmed by immunohistochemistry, as vimentin expression was increased and E-cadherin lost in PDTC compared with adjacent PTC. Moreover, PDTC stained positively for phospho-Smad2, suggesting a role for transforming growth factor (TGF)ß in mediating this process. Accordingly, TGFß-induced EMT in primary cultures of thyroid cells from Tg-Braf mice, whereas wild-type thyroid cells retained their epithelial features. TGFß-induced Smad2 phosphorylation, transcriptional activity and induction of EMT required mitogen-activated protein kinase (MAPK) pathway activation in Tg-Braf thyrocytes. Hence, tumor initiation by oncogenic BRAF renders thyroid cells susceptible to TGFß-induced EMT, through a MAPK-dependent process.

Molecular detection and characterization of circulating tumor cells and micrometastases in prostatic, urothelial, and renal cell carcinomas.

The detection and molecular characterization of circulating tumor cells (CTCs) and micrometastases in urinary tract and prostatic tumors may have important prognostic and therapeutic implications. In the last decade, numerous groups have attempted the detection of occult tumor cells in renal, prostatic, and urothelial carcinomas using the highly sensitive reverse-transcriptase polymerase chain reaction (RT-PCR). In prostatic carcinoma (PC), tissue-specific transcripts were detected with high specificity in the blood of patients with localized and advanced disease. PCR assays for PC detection were shown to be strong predictors of poorer outcome in some reports, while a lack of prognostic significance was found in other studies. There was a vast difference in the PCR positivity rates between various groups studying PC. This discrepancy could be due to variations in PCR methodology. In urothelial and renal cell carcinoma, the amount of research on the subject is still too limited. Currently, these assays for occult tumor cells are promising but are not yet ready to use in PC and urinary tract tumors. Because of the many limitations of PCR (e.g., false positives), many groups are developing new approaches for the detection of occult tumor cells. The most attractive technique involves immunomagnetic isolation of intact CTC and micrometastases prior to downstream analysis. The tumor-rich magnetic fraction can be subjected to RT-PCR, immunocytochemistry, and in situ hybridization. This will lead to better quantification and molecular characterization of these tumor cells.

Hürthle cell carcinoma: a critical histopathologic appraisal.

PURPOSE: Controversy exists over the ability of morphology to predict the biologic behavior of Hürthle cell carcinoma. The aim of this study was to conduct a critical histopathologic review of Hürthle cell carcinoma and to correlate morphologic parameters with clinical outcome. PATIENTS AND METHODS: Patients with histologically confirmed Hürthle cell carcinoma treated between 1940 and 2000 form the basis of this study. Adenomas were excluded. Tumors of unknown malignant behavior ([UMB] n = 17) had solid growth pattern, incomplete capsular invasion (Ci), or both but no vascular invasion (Vi). Minimally invasive carcinomas ([MIC] n = 23) had one focus of intra- or extracapsular Vi, one focus of complete Ci, or both. Widely invasive carcinomas ([WIC] n = 33) demonstrated more than one focus of Vi, more than one focus of Ci, or both. The primary end points were relapse-free survival (RFS) and disease-specific survival (DSS). Rates of recurrence/death were estimated by Kaplan-Meier method. The univariate influence of prognostic factors on end points was analyzed by log-rank test, and multivariate analysis was performed by Cox regression. RESULTS: Median follow-up was 8 years. No patients with UMB or MIC relapsed or died of disease. Of WIC, 73% relapsed and 55% died of disease. Age, size, and extent of resection did not influence outcome. Adverse predictors of RFS and DSS among WIC were extrathyroidal extension, nodal metastasis, positive margin, and solid growth pattern (P <.05). Both Ci and Vi were associated with worse DSS (P <.05). On multivariate analysis, extrathyroidal extension and nodal metastases were independent predictors of outcome (P <.05). CONCLUSION: Patients with Hürthle cell carcinoma have a prognosis that is predicted by well-defined histomorphologic characteristics. Unlike differentiated thyroid cancer, nodal metastases predict a worse outcome in widely invasive Hürthle cell carcinoma, as does extrathyroidal extension.

Preparation by recombinant human thyrotropin or thyroid hormone withdrawal are comparable for the detection of residual differentiated thyroid carcinoma.

Clinical recurrences of differentiated thyroid carcinoma occur in 20% of patients after thyroid surgery. We performed a retrospective analysis of a cohort of patients undergoing routine follow-up testing to detect recurrent thyroid carcinoma over a 2-yr period. One group was prepared for testing by thyroid hormone withdrawal (THW), and the other group remained on thyroid hormone and received injections of recombinant human TSH (rhTSH) before diagnostic whole-body radioiodine scanning (DxWBS). We hypothesized that no differences in the ability to detect residual disease would exist between these 2 groups. Two hundred and eighty-nine patients were examined by both DxWBS and by measurement of the serum thyroglobulin (Tg) response to elevated TSH levels. THW was used for 161 patients, and rhTSH preparation was used for 128 patients. Based on all available testing results, we categorized patients as having metastatic disease, thyroid bed uptake only, or no evidence of disease. We examined the sensitivity, specificity, positive and negative predictive values of the DxWBS, and the stimulated Tg after preparation by THW or rhTSH. Patients with thyroid bed were not considered in accuracy testing. The sensitivity and specificity of the 2 tests were comparable between groups. No significant differences were present in the positive or negative predictive values between groups. The highest negative predictive value (97%) was in patients who had both a negative DxWBS and low stimulated Tg levels after rhTSH. In summary, we were unable to demonstrate a difference in the diagnostic accuracy of DxWBS and/or Tg between patients prepared by either THW or rhTSH. We conclude that preparing patients by rhTSH is diagnostically equivalent to preparing them by THW.

Reverse transcriptase polymerase chain reaction (RT-PCR) detection of melanoma-related transcripts in the peripheral blood and bone marrow of patients with malignant melanoma. What have we learned?

The detection of circulating tumor cells (CTC) and bone marrow micrometastases (BMM) by reverse transcriptase polymerase chain reaction (RT-PCR) may help predict recurrence and survival in malignant melanoma (MM). Since the appearance of the original article by Smith et al. in 1991 (Lancet 338:1227), several groups have attempted the detection of CTC and BMM in MM using RT-PCR for melanocytic specific markers, mainly tyrosinase mRNA. Most studies show that tyrosinase is not present in the PB and BM of control individuals without MM. The PCR positivity rates in MM are extremely variable, ranging from 0% to 100%. There was a correlation between RT-PCR and stage in some but not all of the studies. These disparate findings could in part be explained by differences in RNA extraction and blood separation techniques, to unrecognized contamination leading to false positive results, or differences in patient selection. Despite these discrepancies, we and others have shown that RT-PCR for tyrosinase mRNA in PB is able to predict overall survival (OS) and disease-free survival (DFS) in a statistically significant manner. In AJCC stage II-IV patients rendered surgically free of disease, we found that blood tyrosinase positivity was an independent predictor of OS and DFS. We also found that BM tyrosinase positivity is an independent predictor of DFS in the same group of patients. RT-PCR may help identify subgroups of patients at high risk for early relapse for more aggressive adjuvant therapy. Large prospective studies and interlaboratory quality assurance initiatives are necessary to confirm the accuracy and prognostic value of these RT-PCR assays.

Screening for genetic aberrations in papillary thyroid cancer by using comparative genomic hybridization.

BACKGROUND: Determination of the genetic composition of papillary thyroid cancers may help explain differences in observed clinical behavior. Comparative genomic hybridization (CGH) is a novel molecular cytogenetic assay that allows simultaneous detection of gains, losses, and amplification of genetic information, making it an ideal screening tool. The aim of this study was to identify genetic aberrations occurring in papillary thyroid cancers by using CGH analysis. METHODS: CGH analysis was performed on 21 individual cases of papillary thyroid cancers. Nonparametric statistical comparisons were performed with the Fisher exact test. RESULTS: Genetic abnormalities were identified by CGH in 10 of 21 cases (48%). A recurrent pattern of aberrations was seen in cases where genetic changes were detected, involving losses at chromosome arms 1p and 9q and chromosomes 17, 19, and 22, and gains at chromosome 4 and chromosome arms 5q, 6q, 9q, and 13q. The loss of chromosome 22 was unique to younger patients (P =.05) and was associated with a higher rate of regional lymphatic metastasis (19% vs 80%, P =.02). CONCLUSIONS: Two genetically unique groups of patients were identified by using CGH analysis. One group had no detectable aberrations; the other had a recurrent pattern of aberrations, localizing to the identical chromosomal loci. This pattern of aberrations suggests that the involved loci may contain genes important in thyroid carcinogenesis. The clinical significance of the presence of copy number changes detected by CGH needs to be determined. In addition, molecular cloning of involved genes in each of the aberrations is warranted.

Molecular detection and characterisation of circulating tumour cells and micrometastases in solid tumours.

The detection and molecular characterisation of circulating tumour cells (CTC) and micrometastases may have important prognostic and therapeutic implications. Because their numbers are very small, these tumour cells are not easily detected using conventional methods. In the last decade, numerous groups have attempted to detect occult tumour cells in solid malignancies using the highly sensitive reverse transcriptase polymerase chain reaction (RT-PCR). These assays were in the vast majority directed against tissue-specific markers. PCR was shown to be superior to conventional techniques in detecting occult tumour cells allowing the identification of one malignant cell mixed with 1-10 million normal cells. In some tumours like melanoma and prostatic carcinoma, tissue-specific transcripts were detected with high specificity in the blood of patients with localised and advanced disease. In some reports, PCR was shown to be a strong predictor of poorer outcome. However, due to the many limitations of PCR (e.g false-positives), many groups are developing new approaches for the detection of occult tumour cells. The most attractive technique involves immunomagnetic isolation of CTC and micrometastases prior to downstream analysis. The tumour-rich magnetic fraction can be subjected to RT-PCR, immunocytochemistry and in situ hybridisation. This will lead to better quantification and molecular characterisation of these tumour cells. In conclusion, the molecular detection and characterisation of occult tumour cells offer a great opportunity for better stratifying patients with solid tumours and for developing new prognostic markers and targeted therapies.

Molecular detection of micrometastases and circulating tumor cells in melanoma prostatic and breast carcinomas.

The molecular detection of circulating tumor cells (CTC) and micrometastases may help develop new prognostic markers in patients with solid tumors. In the last 10 years, numerous groups have attempted the detection of occult tumor cells in solid malignancies using the highly sensitive reverse transcriptase polymerase chain reaction (RT PCR) technique. These assays were in the vast majority directed against tissue specific markers. In most studies on prostatic carcinoma, RT PCR was able to specifically detect prostatic tissue specific markers in the peripheral blood (PB), bone marrow (BM) and lymph nodes of patients with localized and metastatic disease. Melanoma related transcripts were detected by RT PCR in the PB, BM and lymph nodes of patients with localized and advanced tumors. In most studies, melanoma related markers were shown to be specific except when assayed in lymph nodes. RT PCR positivity rates were highly variable between studies. Despite tFlese discrepancies, many authors have shown a statistically significant correlation between RT PCR positivity and a poorer outcome in both melanoma and prostatic carcinoma. In breast carcinoma, all markers that have been extensively tested were shown to be non-specific. Because of the many limitations of RT PCR (e.g. false positives), many groups are developing new approaches for the detection occult tumor cells. One of these techniques involves immunobead isolation of CTC and micrometastases prior to down stream analysis. The tumor rich magnetic fraction can be subjected to RT PCR, immunocytochemistry and flow cytometry. In conclusion, the molecular detection of occult tumor cells in solid tumors seems very promising and the techniques used for this purpose are in continuous evolution. Large prospective and interlaboratory variability studies are necessary to determine the accuracy and prognostic value of these assays.

Detection of prostatic specific membrane antigen messenger RNA using immunobead reverse transcriptase polymerase chain reaction.

The present study was performed to detect circulating prostatic carcinoma (PC) cells using a novel three-step immunobead reverse transcriptase (RT) polymerase chain reaction (PCR) assay for prostatic specific membrane antigen (PSMA) messenger RNA (mRNA). The sensitivity and specificity of this technique was assessed and the incidence of immunobead RT-PCR positivity correlated with progressive metastatic disease and serum prostatic specific antigen (PSA) levels. Fifty peripheral blood (PB) samples from 46 patients with PC were incubated with magnetic beads coated with Ber-EP4 antibody directed against the human epithelial antigen a membrane antigen widely expressed by epithelial cells. The epithelial cell-enriched magnetic fraction was then subjected to mRNA isolation using oligo-deoxythymidine (dT) magnetic beads. Nested RT-PCR for PSMA was performed on the mRNA oligo-dT complex and the identity of the RT-PCR products was confirmed by Southern blotting. Twenty-one PB samples from 8 control subjects without PC were also evaluated. Three-step immunobead PSMA RT-PCR was able to detect one PC cell per 1 mL of PB. The positivity rate of the RT-PCR assay was significantly higher (11 of 25; 44%) in patients with metastatic tumor than in patients with non-metastatic disease (1 of 21; 5%) (P = 0.003). In patients with metastatic PC, RT-PCR positivity was much higher in patients with progressive disease (10 of 13; 77%) than in patients with responding or stable disease (1 of 12; 8%) (P = 0.001). There was a statistically significant correlation between immunobead PSMA PCR positivity and high levels of serum PSA (P = 0.005). All control subjects without PC tested negative for PSMA PCR. The three-step immunobead RT-PCR for PSMA can detect circulating PC cells with high specificity and sensitivity. Preliminary data show a strong correlation between immunobead PCR positivity, the presence of progressive metastatic disease, and high levels of serum PSA.

Molecular detection of micrometastases and circulating tumor cells in solid tumors.

The detection of circulating tumor cells and micrometastases may have important prognostic and therapeutic implications. Because their numbers can be very small, these tumor cells are not easily detected using conventional methods. In the last decade, molecular techniques have been widely used for the detection of occult tumor cells. The objective of this report is the application of these molecular tools to solid tumors. A systematic review of all related English-language articles published in the last 32 years was performed. The molecular detection of occult tumor cells can be accomplished by PCR amplification of tumor-specific abnormalities present in the DNA or mRNA of malignant cells. The other main PCR strategy for the detection of CTC and micrometastases involves amplification of tissue-specific mRNA. This latter method was often applied to solid tumors, whereas the former was occasionally used. PCR was shown to be superior to conventional techniques in detecting occult tumor cells, allowing the identification of 1 malignant cell mixed with 1 to 10 million normal cells. In some reports, PCR is shown to be a strong predictor of outcome. The molecular detection of circulating tumor cells and micrometastases in solid tumors can be accomplished using highly sensitive PCR assays. The central question of whether PCR reliably predicts relapse and survival remains unanswered for many types of solid tumor. If PCR-based assays are found to be a reliable tool, they will likely have a major impact on the management of these malignancies.

Association between molecular detection of GAGE and survival in patients with malignant melanoma: a retrospective cohort study.

We used GAGE as a molecular marker to identify melanoma cells with metastatic potential in the peripheral blood and the bone marrow. One hundred thirty-three patients with malignant melanoma (21 clinical stage II, 74 stage III, and 38 stage IV) had a single marrow and/or blood sample drawn immediately prior to surgical resection. Simultaneous bone marrow and blood samples (85 patients), marrow-only samples (35 patients), and blood-only samples (13 patients) were examined for the presence of GAGE expression using reverse transcription-PCR. GAGE expression was associated with adverse overall patient survival, measured from the time of sampling (P = 0.01). When data were stratified for clinical stage, median survival was statistically longer among GAGE-negative patients in the stage III cohort only (P = 0.01). In a multivariate model, only GAGE positivity in blood and/or marrow and clinical stage were significant prognostic variables. It was the detection of GAGE in blood but not marrow that was associated with poor survival. The detection of blood GAGE by reverse transcription-PCR has significant adverse implications for overall survival of patients with malignant melanoma in this cohort, and it warrants further investigation.

Detection of tyrosinase mRNA by reverse transcription-polymerase chain reaction in melanoma sentinel nodes.

BACKGROUND: Sentinel lymph node (SLN) biopsy is an alternative to elective dissection or observation for management of lymph node basins in patients with cutaneous melanomas. The detection of tyrosinase mRNA in melanoma SLN specimens by reverse transcription-polymerase chain reaction (RT-PCR) has been reported to be a more sensitive method to detect subclinical metastases, compared with histological analysis. The aims of this study were to (1) define the yield of RT-PCR in assessing SLNs, compared with histological analysis, (2) identify the incidence of false-positive results in SLNs, and (3) report the rate of actin PCR negativity (i.e., samples with degraded RNA) in SLNs. METHODS: Twenty-eight patients with 1.2-9.6-mm cutaneous melanomas underwent SLN biopsy (between October 1996 and March 1997). One half of each SLN was analyzed by nested RT-PCR for tyrosinase mRNA. The other half of the SLN was examined by routine microscopy. Twenty-one lymph nodes from patients without melanoma were evaluated as controls. RESULTS: Two of the 28 patients with melanoma were excluded because of RNA degradation, as indicated by actin negativity. Six of the remaining 26 patients exhibited melanoma metastases in routine histological examinations. All histologically positive lymph nodes were RT-PCR-positive. Thirteen of the 20 (65%) histologically negative cases were RT-PCR-positive. Of 21 control lymph nodes, 3 were actin-negative and were not assessable for tyrosinase mRNA. Two of the remaining 18 (11%) negative-control nodes were RT-PCR-positive. CONCLUSIONS: Among patients undergoing SLN biopsy, tyrosinase mRNA was detectable in 73% of SLNs from patients at risk for regional nodal metastases, including all of those with histologically positive SLNs. There is a definable false-positive rate for tyrosinase mRNA detection in the lymph nodes of patients who do not have melanoma. Actin verification of RNA integrity is necessary to ensure the accuracy of this test in detecting tyrosinase mRNA. Ongoing follow-up monitoring will define the prognostic value of this assay.

Review: polymerase chain reaction detection of micrometastases and circulating tumor cells: application to melanoma, prostate, and thyroid carcinomas.

The main strategy used for the detection of circulating tumor cells (CTC) and micrometastases in solid tumors is the polymerase chain reaction (PCR) amplification of tissue specific messenger RNA present in the tumor cells. PCR was more sensitive than conventional techniques, allowing the identification of one tumor cell diluted into 1 mL of blood. PCR was shown to be specific in most studies related to the detection of CTC and marrow micrometastases in melanoma and prostate carcinoma (PC). PCR positivity for thyroid markers was reported in the blood of control subjects. Large variations in the PCR positivity rates and the prognostic value of these assays have been encountered in PC and melanoma. There was a correlation between PCR and stage in some but not all the studies. Despite these discrepancies, many investigators have shown PCR to be predictive of outcome in PC and especially in melanoma. PCR in blood and bone marrow was an independent predictor of overall and disease-free survival in melanoma patients rendered surgically free of disease. These tests may help better stratify patients for radical surgeries and adjuvant therapy. Large prospective and interlaboratory studies are needed to confirm the accuracy and prognostic value of these assays.

Anthracotic and anthracosilicotic spindle cell pseudotumors of mediastinal lymph nodes: report of five cases of a reactive lesion that stimulates malignancy.

We report five cases of reactive mediastinal spindle cell proliferations associated with anthracosis and anthracosilicosis that simulated a malignant process both on clinical and morphological grounds. Clinically, the lesions formed radiographically evident masses or were infiltrative. Microscopically, a prominent storiform pattern of intertwining spindle cells was found in four cases. This proliferation extended outside of the lymph node capsule in three cases and surrounded nerves in two. Because of this combination of features, the submitted diagnoses included a malignant neoplasm in four cases. The spindle cells were immunoreactive for histiocytic markers and focally contained fine anthracotic pigment. All cases featured nodular hyaline scars and contained polarizable material suggestive of silica, although a history of industrial exposure was obtained in only two cases. No lesion has enlarged or otherwise progressed during follow-up ranging from 6 to 48 months. The differential diagnosis includes a variety of spindle cell neoplasms, including malignant fibrous histiocytoma, follicular dendritic cell tumor, spindle cell melanoma, and Kaposi's sarcoma.

Prognostic significance of peripheral blood and bone marrow tyrosinase messenger RNA in malignant melanoma.

The objectives of this study were to evaluate the prognostic significance of reverse transcription PCR (RT-PCR) detection of tyrosinase mRNA in the peripheral blood (PB) and bone marrow (BM) of patients with stage II-IV malignant melanoma (MM). Seventy-three PB samples and 109 BM aspirates from 123 assessable patients with stage II-IV MM were analyzed for tyrosinase mRNA using nested RT-PCR. Twenty-five controls without MM were also evaluated. The RT-PCR results were correlated with overall survival (OS) and clinical stage. Overall, 23 of the 123 patients with MM (19%) had tyrosinase mRNA in their blood and/or BM. RT-PCR positivity was present in the PB of 9 of 73 patients (12%), whereas 18 of 109 (16.5%) had tyrosinase mRNA in their BM. All controls were tyrosinase PCR negative. There was no correlation between RT-PCR results and clinical stage. Within stage II, BM PCR-positive patients had a shorter median survival (24 months) than BM PCR-negative individuals (median not reached), with a P approaching significance (P = 0.06). There was a statistically significant correlation between blood PCR positivity and decreased overall survival (P = 0.03) in all patients. Blood PCR positivity was associated with a significantly decreased OS in stage II and III (P = 0.01 and 0.02, respectively) and was not a predictor of OS in stage IV. In multivariate analysis, blood RT-PCR for tyrosinase mRNA was found to be an independent predictor of survival (P = 0.03; risk ratio, 2.87). RT-PCR can specifically detect tyrosinase mRNA in the PB and BM of patients with MM. Blood RT-PCR is an independent predictor of overall survival in stage II-III MM. Additional studies are needed to define the potential role of this assay in the management of patients with advanced melanoma.