A case report of contrast-enhanced harmonic ultrasonography for the diagnosis of an esophageal duplication cyst.

A 54-year-old man was referred to our hospital because of a suspected esophageal submucosal tumor on upper gastrointestinal radiography. Contrast-enhanced computed tomography showed a 52 mm homogeneous mass attached to the lower thoracic esophagus. Esophagogastroduodenoscopy revealed a 50 mm submucosal tumor in the lower esophagus, and endoscopic ultrasonography (EUS) showed a continuous hypoechoic lesion in the esophageal muscularis propria. Contrast-enhanced harmonic EUS revealed a non-echogenic area. T1 and T2 magnetic resonance imaging revealed a high-signal lesion. Based on imaging studies, an esophageal duplication cyst was diagnosed. Although asymptomatic, the patient underwent video-assisted thoracic surgery because of the possibility of rupture and the appearance of symptoms due to a future infection or enlargement, although this was not noted before. In our case, the esophageal duplication cyst appeared as a hypoechoic mass, requiring differentiation from submucosal tumor other than the cyst. Histologically, the cyst was covered by two layers of muscle covered by the chorioepithelial columnar epithelium. EUS fine-needle aspiration is effective in diagnosing submucosal tumor but also carries the risk of infection. Contrast-enhanced ultrasonography was used in this case to observe the interior and reach a preoperative diagnosis. Contrast-enhanced harmonic EUS appears to be effective in examining the interior of submucosal tumor lesions noninvasively.

Impact of background parenchymal enhancement levels on the diagnosis of contrast-enhanced digital mammography in evaluations of breast cancer: comparison with contrast-enhanced breast MRI.

PURPOSE: To compare the diagnostic performances of contrast-enhanced digital mammography (CEDM) and breast MRI in evaluations of breast cancer, with a focus on the impact of background parenchymal enhancement (BPE) levels. METHODS: The present study included women who underwent CEDM and breast MRI to evaluate the disease extent of breast cancer between January 2018 and December 2019. Readers judged BPE levels (minimal-mild or moderate-marked) on CEDM, and were asked to assign findings suggesting malignancy using the following criteria: (1) enhancement other than BPE and (2) BI-RADS 4/5 calcifications without enhancement. On MRI, BI-RADS 3 and BI-RADS 4/5 lesions were evaluated as benign and malignant, respectively. The diagnostic performances of CEDM and MRI were compared separately between women with minimal-mild BPE and those with moderate-marked BPE. RESULTS: Sixty-nine patients comprising 43 postmenopausal and 26 premenopausal women were included in the present study. In total, 195 lesions (94 malignant and 101 benign) were identified. The sensitivity and specificity of CEDM for the diagnosis of all lesions were 90.8 and 91.5% with minimal-mild BPE and 79.3 and 76.2% with moderate-marked BPE, respectively. The sensitivity and specificity of MRI were 90.0% and 71.0% with minimal-mild BPE and 87.5% and 78.1% with moderate-marked BPE, respectively. The accuracy of CEDM was significantly superior to that of MRI in women with minimal-mild BPE on both CEDM and MRI (p = 0.002). Regarding the negative impact of a correct diagnosis on CEDM, the odds ratio of "moderate-marked BPE" was 0.382. CONCLUSION: In patients with minimal-mild BPE, the diagnostic performance of CEDM was superior to that of MRI.

The association between MRI findings and breast cancer subtypes: focused on the combination patterns on diffusion-weighted and T2-weighted images.

PURPOSE: To assess morphology on diffusion-weighted imaging (DWI) and intratumoral signal intensity (SI) on T2-weighted images (T2WI) of breast carcinomas, and to evaluate the association between the combined DWI and T2WI findings and breast cancer subtypes. METHODS: Two hundred and eighty breast cancer patients who underwent breast MRI prior to therapy were included in this retrospective study. All had invasive carcinomas, which were classified into five subtypes: Luminal A-like (n = 149), Luminal B-like (n = 63), Hormone receptor-positive HER2 (n = 31), Hormone receptor-negative HER2 (n = 13), or Triple-negative (TN) (n = 24). Based on the morphology on DWI, the tumors were classified into two patterns: DWI-homogeneous or DWI-heterogeneous. If DWI-heterogeneous, an assessment of intratumoral SI on T2WI was performed: tumors with intratumoral high/low SI on T2WI were classified as Hete-H/Hete-L, respectively. The associations between (1) the morphological patterns on DWI and the five subtypes, and (2) the intratumoral SI patterns on T2WI and the five subtypes in DWI-heterogeneous were evaluated. RESULTS: There was a significant association between (1) the morphological patterns on DWI and the five subtypes (p < 0.0001), and (2) the intratumoral SI patterns on T2WI and the five subtypes in DWI-heterogeneous (p < 0.0001). DWI-homogeneous was dominant in Luminal A-like (67.1%), and Hete-H was dominant in TN type (75%). Hete-H, suggesting the presence of intratumoral necrosis, included high proliferative and/or aggressive subtypes more frequently (80%) than Hete-L, suggesting the presence of fibrotic focus. Fibrotic focus was seen more commonly in the luminal subtypes. CONCLUSION: The combined findings on DWI and T2WI revealed breast carcinomas that were associated with particular subtypes.

Primary Gastrointestinal Stromal Tumor of the Liver with Cystic Changes.

Gastrointestinal stromal tumors (GISTs) are known to originate specifically from the intestinal cells of Cajal located in the gastrointestinal mesenchyme. GISTs developing outside of the digestive tract have barely been reported. We encountered a first case of large primary GISTs in the liver with cystic changes. A 63-year-old man with a past history of brain infarction visited our hospital. The computed tomography (CT) revealed a 6-cm and a 10-cm mass in the right and the caudal lobe of the liver, respectively. These tumors have marginal enhancement in the arterial phase; however, they presented as hypodense in the internal tumor sites. Both liver tumors had cystic changes. Gastrointestinal examinations using endoscopy revealed no other gastrointestinal tumors, and [18F]-fluoro-2-deoxy-D-glucose positron emission tomography/CT revealed multiple bone metastases in addition to the liver tumors. The liver tumor specimens were composed of spindle cells, and the immunohistochemical staining for c-Kit and for DOG1, as discovered on GIST, was positive. The patient was diagnosed with primary hepatic GIST with cystic changes.

Mammary Analogue Secretory Carcinoma Presenting as a Cervical Lymph Node Metastasis of Unknown Primary Site: A Case Report.

BACKGROUND: Mammary analogue secretory carcinoma (MASC) is a pathological entity arising in the salivary glands first described by Skalova et al. [Am J Surg Pathol 2010;34: 599-608]. Here, we report the first case of MASC presenting as a cervical lymph node metastasis of unknown primary site together with a brief review of the literature. CASE REPORT: We present a 74-year-old male with a painless lump in his left neck. Based on the fine-needle aspiration cytological findings, a possible malignant tumor was suspected. No evidence of a primary lesion was observed using imaging modalities including positron emission tomography/computed tomography. The patient underwent an ipsilateral modified radical neck dissection. Immunohistochemical staining showed that the neoplastic cells were positive for S100 protein and GATA3. A rearrangement of the ETV6 gene was noted during fluorescence in situ hybridization, and the final histopathological diagnosis was MASC. CONCLUSION: We encountered a MASC presenting as a cervical lymph node metastasis of unknown primary site. No adjuvant therapy was administered, and no local recurrence or metastatic disease has been detected during a follow-up period of 9 months. This is the first case report of MASC presenting as a cervical lymph node metastasis of unknown primary site and suggests the new properties of MASC.

Is the absolute value of O(6)-methylguanine-DNA methyltransferase gene messenger RNA a prognostic factor, and does it predict the results of treatment of glioblastoma with temozolomide?

OBJECTIVES: Methylation of O(6)-methylguanine-DNA methyltransferase (MGMT) has been reported to be a good prognostic factor for patients with glioblastoma multiforme (GBM). To determine whether the absolute value of MGMT messenger RNA (mRNA) might be a prognostic factor and useful for predicting the therapeutic effectiveness of temozolomide, especially with regard to GBMs, the authors measured the absolute value of MGMT mRNA in gliomas by using real-time reverse-transcription polymerase chain reaction (RT-PCR). METHODS: MGMT mRNA was measured in 140 newly diagnosed gliomas by real-time RT-PCR using the Taq-Man probe. Among 73 GBMs, 45 had been initially treated with temozolomide and radiation. RESULTS: The mean MGMT mRNA value was significantly lower in oligodendroglial tumors than in other tumors. In the 73 GBMs, a significant prognostic factor for progression-free survival was fewer than 1000 copies/ µgRNA of MGMT mRNA (p = 0.0150). Of 45 patients with GBMs that had been treated with temozolomide and radiation, progression-free survival was significantly longer for those whose GMB had fewer than 1000 copies/µgRNA of MGMT mRNA than for those whose GBM had more than 1000 copies/µgRNA (p = 0.0090). In 32 patients with GBMs treated by temozolomide and radiation whose age was younger than 75 years and whose Karnofsky Performance Scale score was more than 70, progression-free and overall survival times were longer for those with GBMs of fewer than 5000 copies/µgRNA of MGMT mRNA than for those with GBMs of more than 5000 copies/µgRNA (p = 0.0365 and p = 0.0312). CONCLUSIONS: MGMT mRNA might be useful as a prognostic factor and for predicting the results of therapy for GBMs treated by temozolomide. New individual adjuvant therapy based on the results of MGMT mRNA quantitation has been proposed.

[Malignant mesotheliomas of the tunica vaginalis testis].

Malignant mesothelioma of the tunica vaginalis is rare, and is usually not diagnosed until surgery is undertaken. We report here a case in a 62-year-old man with malignant mesothelioma tunica vaginalis testis. He was referred to our hospital with a painless swelling of the left scrotal contents. There is a thickening of mesothelia of the tunica vaginalis with left sided hydrocele by ultrasonography and computed tomography scan. The tumor was resected under the diagnosis of testicular malignant tumor. However, the pathologist reported malignant mesothelioma and positive margin. He received external beam radiation therapy at a total dose of 44 Gy. Disease progression was not apparent 2 years after treatment. To our knowledge, 26 cases of malignant mesothelioma in the perineum or intrascrotum have been reported in Japan and this case is thought to be the 27th case in Japan.

[A case of duodenal carcinoid tumor accompanied by liver metastasis and lymph node metastases in a patient with von Recklinghausen disease].

We report a case of duodenal carcinoid tumor accompanied by liver metastasis and lymph node metastases in a patient with von Recklinghausen disease. A 48-year-old woman with von Recklinghausen disease was referred to our hospital because of a submucosal tumor at the ampulla of Vater detected by upper gastrointestinal endoscopy. The lesion was diagnosed as a carcinoid tumor based on the pathology of the biopsy specimen. At operation, although there were liver metastasis on the surface of S3 the liver and regional lymph node metastases, we selected pancreatoduodenectomy with lymph node dissection and enucleation of the liver metastasis. The postoperative course was good and the woman was discharged on postoperative day 33. No recurrence has been seen at 24 months since surgery.

Silent intravascular lymphoma initially manifesting as a unilateral adrenal incidentaloma.

Intravascular large B-cell lymphoma (IVLBCL) is a rare subtype of malignant lymphoma. Although the involvement of adrenal glands in IVLBCL is often observed, primary adrenal IVLBCL is rare. Most reported cases of adrenal IVLBCL showed bilateral lesions resulting in rapidly progressive adrenal failure and poor prognosis. Here, we report a case of slowly progressive primary adrenal IVLBCL manifesting initially with unilateral adrenal incidentaloma. This case is a silent IVLBCL and shows that the enlargement of both adrenal glands can be followed.

Primary mammary mucinous cystadenocarcinoma: cytological and histological findings.

Mucinous cystadenocarcinoma (MCA), commonly encountered in the ovary or pancreas, is rare in the breast and was only recently described as a distinct variant of invasive ductal carcinoma of the breast. Only 11 cases of primary mammary MCA have been reported. In this article, we report a case of primary mammary MCA with focus on cytological and histological findings. A 65-year-old female noticed right palpable breast mass. Sonography showed an irregularly shaped 2.8 × 2.4 cm lesion in the upper outer quadrant of the right breast. Fine-needle aspiration cytology was performed on the right breast nodule, and cytopathologic examination suggested an adenocarcinoma composed of tall columnar cells with mucin. A partial mastectomy of the right breast and the axillary lymph nodes dissection was performed. The gross examination revealed a well-demarcated and mucus-filled tumor. Histologically, it had complex papillae, some of which were supported by delicate fibrovascular stroma lined by simple to slightly stratified columnar neoplastic epithelial cells with intracellular mucin, coexisting with MCA in situ and ordinary intraductal carcinoma component (ICC). Immunohistochemically, ICC was HER2-negative and estrogen receptor/progesterone receptor-positive, while MCA was triple negative. MCA might be derived from a metaplasia of ordinary ICC, but its pathogenesis and biologic behavior remains unclear. Despite the invasive nature of mammary MCA, these carcinomas appear to be associated with a good prognosis. The patient has remained well and disease-free for 6 months after the operation.

Sensitivity and specificity in transcranial motor-evoked potential monitoring during neurosurgical operations.

BACKGROUND: Intraoperative transcranial motor-evoked potential (TCMEP) monitoring is widely performed during neurosurgical operations. Sensitivity and specificity in TCMEP during neurosurgical operations were examined according to the type of operation. METHODS: TCMEP monitoring was performed during 283 neurosurgical operations for patients without preoperative motor palsy, including 121 spinal operations, 84 cerebral aneurysmal operations, and 31 brain tumor operations. Transcranial stimulation at 100-600 V was applied by screw electrodes placed in the scalp and electromyographic responses were recorded with surface electrodes placed on the affected muscles. To exclude the effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supramaximal stimulation of the peripheral nerve immediately after transcranial stimulation was used for compensation of TCMEP. RESULTS: In spinal operations, with an 80% reduction in amplitude as the threshold for motor palsy, the sensitivity and specificity with CMAP compensation were 100% and 96.4%, respectively. In aneurysmal operations, with a 70% reduction in amplitude as the threshold for motor palsy, the sensitivity and specificity with CMAP compensation were 100% and 94.8%, respectively. Compensation by CMAP was especially useful in aneurysmal operations. In all neurosurgical operations, with a 70% reduction in amplitude as the threshold for motor palsy, the sensitivity and specificity with CMAP compensation were 95.0% and 90.9%, respectively. CONCLUSIONS: Intraoperative TCMEP monitoring is a significantly reliable method for preventing postoperative motor palsy in both cranial and spinal surgery. A 70% reduction in the compensated amplitude is considered to be a suitable alarm point in all neurological operations.

Cervical unilateral open-door laminoplasty with titanium miniplates through newly designed hydroxyapatite spacers.

A newly designed hydroxyapatite (HA) spacer for cervical laminoplasty is provided with a hole through which the titanium miniplate is passed. A new method of unilateral open-door laminoplasty with titanium miniscrew and miniplate through this HA spacer is described. Twenty-two patients with cervical stenotic disorders were treated by this procedure. Only the predominantly affected side of the laminae is exposed. The supraspinous and interspinous ligaments and the deep muscle layer in the contralateral side are left intact. A 4-mm wide gutter near the intervertebral joint is made and contralateral hinges are made under the deep muscle layer with minimum detachment of these muscles. The opened lamina is fixed with the titanium miniplate passed through the hole in the newly designed HA spacer. Mean operative time for the 22 operations was 193.5 minutes. Mean enlargement of the minimum spinal canal diameter was 50.9%. Neurological outcomes after 3 months were evaluated according to the Japanese Orthopaedic Association (JOA) scoring. Mean recovery rate of JOA score by Hirabayashi's method was 49.5%. Only 2 patients reported postoperative axial neck pain. Our method for unilateral open-door laminoplasty provides adequate decompression and tight fixation of laminae, and is less invasive to the posterior supporting elements of cervical spine.

Immunohistochemical staining of Reg IV and claudin-18 is useful in the diagnosis of gastrointestinal signet ring cell carcinoma.

Signet-ring cell carcinoma (SRCC) is a unique subtype of adenocarcinoma that is characterized by abundant intracellular mucin accumulation and a crescent-shaped nucleus displaced toward one end of the cell. Identification of an SRCC's primary site is important for better planning of patient management because the treatment and prognosis differs markedly depending on the origin of the SRCC. In the present study, we analyzed the immunohistochemical characteristics of 94 cases of SRCC, including 21 cases of gastric SRCC, 16 of colorectal SRCC, 10 of breast SRCC, and 47 of pulmonary SRCC, with antibodies against Reg IV and claudin-18, which we previously identified as gastric cancer-related genes. We also tested known markers cytokeratin 7, cytokeratin 20, MUC2, MUC5AC, caudal-related homeobox gene 2 (CDX2), thyroid transcription factor-1, mammaglobin, gross cystic disease fluid protein 15, and estrogen receptor. All 21 cases of gastric SRCC and 16 cases of colorectal SRCC were positive for Reg IV, and the remaining SRCCs were negative. Eighteen of 21 (86%) gastric SRCCs and 6 of 16 (38%) colorectal SRCCs were positive for claudin-18, whereas another SRCCs were negative. In conclusion, Reg IV staining and claudin-18 staining can aid in diagnosis of gastrointestinal SRCC.

Primary pulmonary malignant peripheral nerve sheath tumor: a case report.

BACKGROUND: Although the histologic features of malignant peripheral nerve sheath tumor (MPNST) have been described, the cytologic features of primary pulmonary MPNST have not been reported in the literature. CASE: We report a case of primary pulmonary MPNST in a 78-year-old man. Follow-up computed tomography of colon cancer, renal cancer, penile cancer and gingival cancer revealed a nodular lesion, 12 mm in diameter, in the right upper lobe of the lung. In frozen section, a diagnosis of malignant neoplasm, not otherwise specified, was rendered for the imprinting specimen and histologic specimen. Imprinting specimens were composed of small cellular aggregates and discohesive neoplastic cells with obvious malignant features. Histologically, spindle cells with pleomorphic nuclei arranged infascicular patterns and multinucleated tumor giant cells were also observed. More than 25 mitotic figures were observed per 10 high-power fields. Tumor cells were positive only for vimentin and S-100, and the Ki-67 labeling index was 10%. Clinical and imaging investigation failed to identify an alternative primary site. We histologically diagnosed this case as primary pulmonary MPNST. CONCLUSION: MPNST has a varied cytomorphology with frank nuclear atypia showing no definite differentiation. Multinucleated neoplastic giant cells with immunopositivity for S-100 may permit more accurate diagnosis of MPNST.

Poorly differentiated neuroendocrine cell carcinoma of the rectum: report of a case and literal review.

A 56-year-old man was admitted to our hospital because of anal bleeding. Colonoscopy and barium enema revealed type 4 tumor in the rectum. Biopsy revealed poorly differentiated adenocarcinoma. Low anterior resection with total mesorectal excision and lymph node dissection was performed. In immunohistochemical staining, chromogranin A and synaptophysin were positive at major lesion, and CEA were focal positive. The resected tumor was diagnosed pathologically as neuroendocrine cell carcinoma. The Ki-67 labeling index (LI) was 87.8%, so proliferative activity and potential malignancy was very high. Multiple metastatic tumors appeared in pelvis and lung eight months after operation. Treatment for neuroendocrine cell carcinoma of the rectum was controversial. Surgical resection and adjuvant chemotherapy might be one of the methods for gastrointestinal neruroendocrine cell carcinoma.

Bizarre parosteal osteochondromatous proliferation with a t(1;17) translocation.

Bizarre parosteal osteochondromatous proliferation (BPOP) is a benign lesion that tends to recur repeatedly. Histologically, BPOP contains three components (cartilage, bone, and spindle cells) in differing amounts. The histological findings of BPOP are similar to those of florid reactive periostitis (FRP) and subungual (Dupuytren's) exostosis. Some authors have postulated that all of these conditions are reactive proliferative lesions representing different phases of reactive processes. Whether BPOP is a reactive proliferative lesion or a neoplastic lesion, however, remains controversial. Recently, a t(1;17)(q32;q21) translocation in BPOP was detected using chromosome banding and fluorescence in situ hybridization (FISH) analyses. Here, we describe a 39-year-old Japanese female with BPOP arising in the proximal phalanx of her third toe. A cytogenetic analysis revealed a t(1;17)(q 42;q23) translocation. The breakpoints in this case are located close to those of previously reported cases. These results suggest that t(1;17) is a distinct translocation of BPOP and that BPOP is a neoplastic lesion, rather than a reactive proliferative process.

Cytoplasmic expression of fibroblast growth factor receptor-4 in human pituitary adenomas: relation to tumor type, size, proliferation, and invasiveness.

The pathogenesis of pituitary adenomas remains unknown. A pituitary tumor-derived (ptd) isoform of fibroblast growth factor receptor-4 (ptd-FGFR4) has been implicated in the neoplastic process. To further understand the expression of FGFR4 in sporadic human pituitary adenomas, we studied 137 pituitary adenomas of various types (102 adenomas from Japanese patients and 35 adenomas from Canadian patients) and 10 nontumorous pituitaries using a polyclonal antiserum that recognizes the C terminus of FGFR4 and analyzed possible relationships among expression of FGFR4, patient nationality, tumor type, size, invasion, and the labeling index of the proliferation marker Ki-67 using the MIB-1 antibody. Cytoplasmic expression of FGFR4 protein was observed in 57.8% of Japanese cases and 62.8% of Canadian cases. FGFR4 reactivity was absent in all 10 normal adenohypophysial tissues examined. FGFR4 expression in pituitary adenomas was restricted mainly to the cytoplasm, a pattern similar to that seen in rat pituitary cells transfected with human ptd-FGFR4 but different from that of cells transfected with wild-type FGFR4, which displayed membrane localization of staining. Protein from primary human adenomas migrated as a 65-kDa species consistent with the predicted size of ptd-FGFR4. FGFR4 protein expression was frequently found in adenomas containing GH, ACTH, or FSH/LH and was also found in null cell adenomas, but reactivity was relatively rare in prolactin-containing adenomas in both Japanese and Canadian groups. The expression of FGFR4 protein was stronger in macroadenomas than in microadenomas (P = 0.02) and high levels of FGFR4 expression (moderate or greater density staining) were more frequently observed in macroadenomas than in microadenomas (P < 0.05). High levels of FGFR4 expression also correlated significantly with the proliferation marker Ki-67 (P = 0.002) and tended (but not significantly) to be found in invasive tumors. These data are consistent with a role for ptd-FGFR4 in pituitary tumorigenesis in a majority of human pituitary adenomas. Moreover, detection of FGFR4 cytoplasmic staining may provide an ancillary diagnostic tool in the diagnosis of pituitary adenoma, particularly in equivocal cases.

Esophageal xanthoma: report of two cases and a review of the literature.

So far, three cases of esophageal xanthoma have been reported. We describe here endoscopic, microscopic and immunohistochemical findings of two new cases of this rare condition, and a review of five cases of esophageal xanthoma, including our cases. Esophageal xanthomas endoscopically show yellow granular spots or a slightly elevated lesion, and are similar to an ectopic sebaceous gland. Microscopically, an aggregate of foamy histiocytes (lipid islands) is seen immediately beneath the squamous epithelium, particularly between the rete ridges. Immunohistochemically, xanthoma cells are positive for CD68, which indicate a histiocytic origin. The etiology of esophageal xanthoma remains unclear. We emphasize that esophageal xanthomas may have been erroneously diagnosed as an ectopic sebaceous gland on endoscopic examination.

Cytology of pleomorphic lobular carcinoma with apocrine cell differentiation of the breast. A case report.

BACKGROUND: Pleomorphic lobular carcinoma (PLC) with apocrine differentiation is a rare breast carcinoma, and its cytologic findings have not been reported before. CASE: A 75-year-old woman had a mass in and skin rash on the left breast. Apocrine carcinoma was suggested on aspiration cytology of the mass. The cytologic smears showed a small number of rounded to oval, atypical cells that were poorly cohesive and individually scattered. The cytoplasm was relatively abundant and contained coarse granules and dropletlike, orange granules (Lendrum's granules). The cell border was distinct. Some atypical cells had intracytoplasmic lumina. The nucleoli were round and prominent, and nuclear chromatin was finely granular. The background was clean. Histologically, the tumor cells proliferated mainly in an Indian file pattern and showed a concentric, targetoid pattern around the non-neoplastic ducts. The cytoplasm was abundant, eosinophilic, granular, positive for the periodic acid-Schiff reaction and diastase resistant. Immunohistochemically the tumor cells were positive for gross cystic disease fluid protein-15 (GCDFP-15) and negative for E-cadherin. Lendrum's granules showed positive expression of GCDFP-15 and lysozyme. CONCLUSION: PLC with apocrine differentiation and apocrine carcinoma may be cytologically confused. Poor cellularity, less cohesiveness, finely granular chromatin, a nonpolyhedral cellular outline and clean background indicate the former rather than the latter. It is important to be aware that PLC presents a variety of cytologic configurations.