Histopathology-guided mass spectrometry differentiates benign nevi from malignant melanoma.

PURPOSE: Distinguishing benign nevi from malignant melanoma using current histopathological criteria may be very challenging and is one the most difficult areas in dermatopathology. The goal of this study was to identify proteomic differences, which would more reliably differentiate between benign and malignant melanocytic lesions. METHODS: We performed histolpathology - guided mass spectrometry (HGMS) profiling analysis on formalin-fixed, paraffin embedded tissue samples to identify differences at the proteomic level between different types of benign nevi and melanomas. A total of 756 cases, of which 357 cases of melanoma and 399 benign nevi, were included in the study. The specimens originated from both biopsies (376 samples) and tissue microarray (TMA) cores (380 samples). After obtaining mass spectra from each sample, classification models were built using a training set of biopsy specimens from 111 nevi and 100 melanomas. The classification algorithm developed on the training data set was validated on an independent set of 288 nevi and 257 melanomas from both biopsies and TMA cores. RESULTS: In the melanoma cohort, 239/257 (93%) cases classified correctly in the validation set, 3/257 (1.2%) classified incorrectly, and 15/257 (5.8%) classified as indeterminate. In the cohort of nevi, 282/288 (98%) cases classified correctly, 1/288 (0.3%) classified incorrectly, and 5/288 (1.7%) were indeterminate. HGMS showed a sensitivity of 98.76% and specificity of 99.65% in determining benign vs malignant. CONCLUSION: HGMS proteomic analysis is an objective and reliable test with minimal tissue requirements, which can be a helpful ancillary test in the diagnosis of challenging melanocytic lesions.

Reconsidering the H&E stain as the gold standard in assessing the depth of burn wounds.

While histological examination is considered by most as the gold standard for burn depth assessment, it has no practical use in the clinical setting. It has, however, been used in the research setting, as a mean for evaluating emerging techniques of depth measurement. Due to the limitations of the H&E stain, other stains have also been explored, such as lactate dehydrogenase (LDH), as presented in this issue, in "Improving the Histologic Characterization of Burn Depth." As the determination of burn depth is not a typical subject in dermatopathology, a summary of selected techniques and the possible role for the LDH stain in future research, is described herein.

Imaging mass spectrometry assists in the classification of diagnostically challenging atypical Spitzoid neoplasms.

BACKGROUND: Previously, using imaging mass spectrometry (IMS), we discovered proteomic differences between Spitz nevi and Spitzoid melanomas. OBJECTIVE: We sought to determine whether IMS can assist in the classification of diagnostically challenging atypical Spitzoid neoplasms (ASN), to compare and correlate the IMS and histopathological diagnoses with clinical behavior. METHODS: We conducted a retrospective collaborative study involving centers from 11 countries and 11 US institutions analyzing 102 ASNs by IMS. Patients were divided into clinical groups 1 to 4 representing best to worst clinical behavior. The association among IMS findings, histopathological diagnoses, and clinical groups was assessed. RESULTS: There was a strong association between a diagnosis of Spitzoid melanoma by IMS and lesions categorized as clinical groups 2, 3, and 4 (recurrence of disease, metastases, or death) compared with clinical group 1 (no recurrence or metastasis beyond a sentinel node) (P < .0001). Older age and greater tumor thickness were strongly associated with poorer outcome (P = .01). CONCLUSIONS: IMS diagnosis of ASN better predicted clinical outcome than histopathology. Diagnosis of Spitzoid melanoma by IMS was strongly associated with aggressive clinical behavior. IMS analysis using a proteomic signature may improve the diagnosis and prediction of outcome/risk stratification for patients with ASN.

Herpes zoster granulomatous dermatitis: histopathologic findings in a case series.

Several types of cutaneous reactions have been reported to arise at the site of herpes zoster (HZ) infection weeks to years after the acute disease. Among these, granulomatous reactions are the most frequently reported. In this study, we describe the spectrum of histopathologic findings of HZ granulomatous reactions observed in 26 patients with cutaneous lesions confined to the area of previous HZ eruption and compare them with biopsy specimens taken from 25 patients with acute HZ. All patients with persistent reactions from whom history was available presented within 12 weeks of the onset of the acute eruption. The most frequent findings were interstitial granulomatous dermatitis with lymphocytes, histiocytes and multinucleated giant cells displaying elastophagocytosis and a perineural, perivascular and perieccrine mononuclear inflammatory infiltrate rich in lymphocytes and plasma cells. Less common features included intra-arrector and peri-arrector pili granulomas, follicular dilatation and hyperkeratosis, and vasculitis. Specimens from patients with acute HZ were found to have small numbers of perineural plasma cells and most had subtle granulomatous inflammation, in patterns similar to the group with late granulomatous reactions. Our findings suggest that granulomatous reactions to varicella zoster virus represent a persistent evolving inflammatory reaction after acute infection.

Polyomavirus-associated Trichodysplasia spinulosa involves hyperproliferation, pRB phosphorylation and upregulation of p16 and p21.

Trichodysplasia spinulosa (TS) is a proliferative skin disease observed in severely immunocompromized patients. It is characterized by papule and trichohyalin-rich spicule formation, epidermal acanthosis and distention of dysmorphic hair follicles overpopulated by inner root sheath cells (IRS). TS probably results from active infection with the TS-associated polyomavirus (TSPyV), as indicated by high viral-load, virus protein expression and particle formation. The underlying pathogenic mechanism imposed by TSPyV infection has not been solved yet. By analogy with other polyomaviruses, such as the Merkel cell polyomavirus associated with Merkel cell carcinoma, we hypothesized that TSPyV T-antigen promotes proliferation of infected IRS cells. Therefore, we analyzed TS biopsy sections for markers of cell proliferation (Ki-67) and cell cycle regulation (p16ink4a, p21waf, pRB, phosphorylated pRB), and the putatively transforming TSPyV early large tumor (LT) antigen. Intense Ki-67 staining was detected especially in the margins of TS hair follicles, which colocalized with TSPyV LT-antigen detection. In this area, staining was also noted for pRB and particularly phosphorylated pRB, as well as p16ink4a and p21waf. Healthy control hair follicles did not or hardly stained for these markers. Trichohyalin was particularly detected in the center of TS follicles that stained negative for Ki-67 and TSPyV LT-antigen. In summary, we provide evidence for clustering of TSPyV LT-antigen-expressing and proliferating cells in the follicle margins that overproduce negative cell cycle regulatory proteins. These data are compatible with a scenario of TSPyV T-antigen-mediated cell cycle progression, potentially creating a pool of proliferating cells that enable viral DNA replication and drive papule and spicule formation.

Trichodysplasia spinulosa is characterized by active polyomavirus infection.

BACKGROUND: Recently a new polyomavirus was identified in a patient with trichodysplasia spinulosa (TS), a rare follicular skin disease of immunocompromised patients characterized by facial spines and overgrowth of inner root sheath cells. Seroepidemiological studies indicate that TSPyV is ubiquitous and latently infects 70% of the healthy individuals. OBJECTIVE: To corroborate the relationship between active TSPyV infection and TS disease by analyzing the presence, load, and precise localization of TSPyV infection in TS patients and in controls. STUDY DESIGN: TS lesional and non-lesional skin samples were retrieved from TS patients through a PubMed search. Samples were analyzed for the presence and load of TSPyV DNA with quantitative PCR, and for expression and localization of viral protein with immunofluorescence. Findings obtained in TS patients (n=11) were compared to those obtained in healthy controls (n=249). RESULTS: TSPyV DNA detection was significantly associated with disease (P<0.001), with 100% positivity of the lesional and 2% of the control samples. Quantification revealed high TSPyV DNA loads in the lesional samples (∼10(6)copies/cell), and low viral loads in the occasionally TSPyV-positive non-lesional and control samples (<10(2)copies/cell). TSPyV VP1 protein expression was detected only in lesional TS samples, restricted to the nuclei of inner root sheath cells over-expressing trichohyalin. CONCLUSIONS: The high prevalence and load of TSPyV DNA only in TS lesions, and the abundant expression of TSPyV protein in the affected hair follicle cells demonstrate a tight relation between TSPyV infection and TS disease, and indicate involvement of active TSPyV infection in TS pathogenesis.

Pseudocarcinomatous hyperplasia with follicular differentiation overlying basal cell carcinoma.

We present a series of 25 cases of basal cell carcinoma (BCC) with overlying cytologically bland epidermal hyperplasia and cyst formation. Eight of the BCCs were nodular and 11 were infiltrative. Immunohistochemical staining for Ki-67 and cytokeratin 17 (CK17) was performed to evaluate the proliferative and differentiation characteristics of the hyperplastic epithelium compared with the adjacent BCC and normal epidermis. Fourteen of the 25 cases had sufficient tissue to evaluate the staining patterns. In the majority of cases, Ki-67 expression was prominent throughout the BCCs, but only expressed in the basal and suprabasal layers of the adjacent hyperplastic epithelium, which was equivalent to normal epidermis. CK17 expression was prominent throughout the BCC and surrounding incident hair follicles. CK17 was expressed to a lesser extent in the central more keratinized portions of the hyperplastic epithelium, but rarely in normal epidermis. The morphologic characteristics and immunohistochemical staining patterns in these tumors suggest that the epidermal hyperplasia represents pseudocarcinomatous hyperplasia with follicular differentiation. Recognizing this pattern of epidermal change should alert the pathologist to the possibility of an associated BCC in cases in which the biopsy specimen or sectioning is initially too superficial to reveal the underlying malignancy.

The inadequacy of punch-excised melanocytic lesions: sampling through the block for the determination of "margins".

BACKGROUND: Dermatopathologists often are asked by clinicians to report margins on punch excisions of melanocytic lesions. OBJECTIVE: We sought to determine the adequacy of surgical margins on melanocytic lesions submitted with intention of complete excision using punch removal technique. METHODS: We conducted prospective analysis of surgical margins on 266 consecutive patients who underwent attempted complete removal of 405 melanocytic nevi submitted as punch and fusiform excisions. RESULTS: Of 206 nonbisected punch excisions, 127 (62%) had final positive margins. Of 159 bisected punch excisions, 76 (48%) had final positive margins. Of 40 elliptical excisions, two (5%) had final positive margins. LIMITATIONS: Information on the perilesional rim of nonpigmented skin included in the excision was not available. CONCLUSIONS: Of punch excisions, 56% had positive margins. Importantly, 30% of these punch excised specimens were negative on initial levels but had positive margins after extensive sectioning, affirming that fusiform excisions are the preferred method to evaluate margins in melanocytic lesions.

CD22 expression on blastic plasmacytoid dendritic cell neoplasms and reactivity of anti-CD22 antibodies to peripheral blood dendritic cells.

We identified CD22 expression on a blastic plasmacytoid dendritic cell (pDC) neoplasm presenting as a leukemia in a child. CD22 expression, as determined by the antibody s-HCL-1, was also noted on the neoplastic cells from three additional patients with blastic pDC tumors identified at our institution. Subsequently we determined that peripheral blood pDCs react with the s-HCL-1 antibody demonstrating that normal pDCs express CD22. Evaluation of five additional anti-CD22 antibodies indicated that staining of pDCs with these reagents was poor except for s-HCL-1. Therefore, the detection of CD22 on pDCs is best demonstrated with the use of this specific antibody clone. All anti-CD22 antibodies stained conventional DCs. We also evaluated the reactivity of the anti-CD22 antibodies with basophils and noted that the pattern of staining was similar to that seen with pDCs. The studies demonstrate that normal DCs and pDC neoplasms express CD22, and highlight clone specific differences in anti-CD22 antibody reactivity patterns on pDCs and basophils.

Benign lymphangiomatous papules of the skin.

Benign lymphangiomatous papules of the skin are benign lymphatic proliferations that may arise in the skin after operation or radiation therapy. We report a case of benign lymphangiomatous papules of the skin that occurred in a patient 4 years after undergoing radiation therapy to the chest for adenocarcinoma of the breast.

Monophasic sarcomatoid carcinoma of the scalp: a case mimicking inflammatory myofibroblastic tumor and a review of cutaneous spindle cell tumors with myofibroblastic differentiation.

BACKGROUND: The evaluation of malignant cutaneous spindle cell tumors is challenged by a diagnostic differential that comprises neoplasms of diverse histogenesis, and a broad immunohistochemical panel may confound the diagnosis when the results suggest multiple lines of differentiation, such as with a combined myofibroblastic and epithelial phenotype. METHODS: We report the case of a solitary scalp nodule that quickly became locally metastatic. A comprehensive panel of immunohistochemistry markers and electron microscopy was evaluated to determine the differentiation of the spindle cells. RESULTS: The tumor, consisting of wavy and slender spindle cells with predominantly bland nuclei, showed immunoreactivity to vimentin, smooth muscle actin, and muscle-specific actin. AE1/AE3, CK5/6, and MNF-116 antibodies were weakly positive in rare cells. However, 34betaE12 showed diffuse positivity in the spindle cell population, thus supporting the diagnosis of a sarcomatoid carcinoma with myofibroblastic differentiation. CONCLUSIONS: The use of 34betaE12 is essential for the evaluation of myofibroblastic spindle cell tumors with rare cytokeratin reactivity. However, even with immunohistochemical and electron microscopic studies, the diagnosis of spindle cell tumors can be confounded by the multiplicity of nosologic equivalents, such as carcinosarcoma, spindle cell carcinoma, and metaplastic carcinoma. The nomenclature of these spindle cell tumors is discussed.

Melanoma associated with pseudoepitheliomatous hyperplasia: a case series and investigation into the role of epidermal growth factor receptor.

BACKGROUND: Pseudoepitheliomatous hyperplasia (PEH) is a reactive epithelial proliferation that occurs in response to underlying infectious, inflammatory, and neoplastic conditions. The histologic features of PEH may simulate squamous cell carcinoma and may obscure an underlying malignant process. The association of PEH with benign melanocytic nevi is well described in the literature. However, reports documenting the association of PEH with melanoma are rare. METHODS: We examined the demographic and histologic features in 13 cases of melanoma in association with PEH. In addition, we evaluated the possible pathogenic role of epidermal growth factor receptor (EGFR) using immunohistochemical methods. RESULTS: In each case, histologic examination revealed epidermal hyperplasia with irregular cords of well-differentiated epithelial cells extending into the dermis and infiltrating the melanoma. Although overlap existed, two patterns of epidermal hyperplasia were noted. The majority of cases (69%) exhibited acanthosis, hyperkeratosis, papillomatosis, and irregular infiltrating epithelial cords with squamous eddies. The remaining cases demonstrated basaloid acanthosis, laminated orthokeratosis, and horn cysts. EGFR immunohistochemical studies revealed strong staining within the basal layer of the epithelium, with no discernible difference between the hyperplastic epithelium overlying the melanoma cells and adjacent normal skin. Immunostaining among the melanoma cells was absent to weak in each of the cases. All cases exhibited intense EGFR immunoreactivity in macrophages underlying the epidermal lesions. CONCLUSIONS: Melanoma is capable of presenting in a variety of histologic guises, including a pattern with PEH. The etiology of PEH, as rarely seen in conjunction with melanoma, unlikely involves EGFR and remains to be elucidated.

An investigation of apoptosis in androgenetic alopecia.

While the androgens, including dihydrotestosterone (DHT), have been implicated in the development of androgenetic alopecia (AGA), the exact mechanism by which they exert their effects is unknown. As apoptosis is an integral component of the normal cycling of human hair, we investigated individuals clinically affected by AGA to assess whether objective differences in the expression of apoptosis related immunohistochemical markers could be observed in scalp biopsies. Specimens from 13 alopecic male cadavers were stained with bcl-2 and terminal deoxynucleotidetransferase dUTP fluorescein nick end-labeling (TUNEL) methods to assess apoptotic activity in affected and unaffected areas of the scalp. Immunoreactivity was analyzed by quantifying nuclear staining differences within the same individual. Sections from two living human volunteers were obtained to establish the method validity. Significant differences in bcl-2 expression were observed between areas of the scalp clinically affected and unaffected by AGA. The Gaussian distribution of bcl-2 staining suggests that a relatively uniform population of follicles exists at the frontal hairline and/or synchrony of follicular cycling occurs in AGA. The apoptosis "hot spot" described by TUNEL staining in the bulge-isthmus region of the murine follicle is also identifiable in the human follicle.

Malignant peripheral nerve sheath tumor with perineurial differentiation: "malignant perineurioma".

BACKGROUND: Although benign tumors derived from the nerve sheath perineurial cell have been described from a variety of anatomic sites and are known to be a component of a number of benign neoplasms, malignant nerve sheath tumors of perineurial origin are exceedingly uncommon. METHODS: We report an unusual case of a 70-year-old male who presented with a rapidly growing mass of the left arm, subsequently shown to be a malignant nerve sheath tumor with perineurial differentiation. A brief microscopic differential diagnosis and review of the literature are discussed. RESULTS: Histologic sections show a partially circumscribed tumor of atypical spindle cells arranged in sweeping fascicles embedded in a myxoid matrix with focal whorling. Nuclear pleomorphism was evident among scattered typical and atypical mitotic figures (mean mitotic index of 7/10 high-power fields). The immunophenotypic profile consisted of only vimentin and epithelial membrane antigen (EMA) positivity, while antibodies to S-100, CD34, smooth muscle actin, and pankeratins were negative. Ultrastructural features included spindle cells with long cytoplasmic processes invested by interrupted basal lamina and pinocytotic vesicles, consistent with perineurial differentiation. CONCLUSIONS: While the histogenic source of the benign perineurioma, the perineurial cell has only rarely been described in conjunction with malignant tumors. All cases to date have shown EMA-positive and S-100-negative atypical spindled cells arranged in fascicles embedded in a myxoid matrix. In addition to immunohistochemistry, ultrastructural examination may be necessary to support the diagnosis. The diagnostic differential includes melanoma, spindle cell squamous cell carcinoma, atypical fibroxanthoma, leiomyosarcoma, and conventional malignant peripheral nerve sheath tumor, most commonly of Schwannian differentiation. Recognizing perineurial differentiation is important since few cases have been reported to date and the biological potential of these neoplasms is not known.

Rhabdomyomatous mesenchymal hamartoma: an unusual dermal entity with a report of two cases and a review of the literature.

BACKGROUND: Rhabdomyomatous mesenchymal hamartoma (RMH) is a rare congenital lesion of the dermis and soft tissues consisting of a disordered and varied collection of mature adipose tissue, skeletal muscle, adnexal elements and nerve bundles. This entity exists under various names including striated muscle hamartoma, congenital midline hamartoma, and hamartoma of cutaneous adnexa and mesenchyme. Several published cases report the occurrence of RMH within the setting of other uncommon congenital abnormalities. METHODS: We report the clinical and pathologic features of two cases of rhabdomyomatous mesenchymal hamartoma. Patient 1 is a 71-year-old man who presented for removal of a nodule located on his temple that had been traumatized during a recent haircut. Patient 2 is a 4-month-old infant with amnion rupture sequence and rare craniofacial abnormalities including facial clefts, microphthalmia, bilateral colobomas, and a mobile fingerlike projection above the left medial canthus. RESULTS: Histological examination in both cases showed a deep dermal and subcutaneous fat collection of disorganized skeletal muscle fibers, adipose and neural tissue, and adnexal structures. Characteristically, the skeletal muscle approximated folliculosebaceous structures in a haphazard manner. CONCLUSIONS: RMH is a rare benign condition of the deep dermis and subcutaneous fat with only 22 cases existing in the English literature. To our knowledge, this is the first report of an elderly man presenting with RMH, presumptively present since birth. There was no evidence of cellular or malignant degeneration. While the etiology of RMH is unknown, possible explanations include aberrancy in the embryonic migration of mesodermally derived tissues or a genetic defect predisposing to the formation of hamartomas.