Ectopic hamartomatous thymoma: a clinicopathological and immunohistochemical study of two cases / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the clinicopathological and immunohistochemical features of ectopic hamartomatous thymoma (EHT), and to discuss its histogenesis.</p><p><b>METHODS</b>The clinical and pathologic features of two EHT cases of were evaluated. Immunohistochemical study was performed by LSAB method using a panel of antibodies including AE1/AE3, CK5, CK7, CK8, CK20, EMA, vimentin, CD5, CD10, alpha-SMA, calponin, desmin, CD34, S-100 protein, CD57, GFAP, TTF-1 and CD99.</p><p><b>RESULTS</b>Both cases occurred in males aged 20 years and 40 years respectively. Each patient presented with a solitary mass, one located in the suprasternal fossa and the other in the left supraclavicular region for a period of 6 months and 2 months respectively. Grossly, the masses were well-circumscribed with spherical and ovoid appearance, measuring 5 cm and 3 cm in maximum diameter respectively. On cut section, they were gray-white in color and of soft consistency. Histologically, both tumors were composed of a mixture of spindle cells, epithelial cells and mature adipose tissue. The spindle cells element accounted 85% and 70% each in the two cases. They resembled fibroblasts in morphology and were arranged frequently in fascicular, woven or storiform patterns. Epithelial cells element represented nearly 10% in both cases. Most of the epithelial cells had a non-keratinization squamous appearance. They formed small solid islands and adamantinoma-like "nastomosing cords", or appeared as lining cells in large cystic spaces. In focal areas, glandular differentiation presented as small glands. A transition between the spindle cell and epithelium components could be also identified in some areas. Mature adipose tissue was irregularly distributed in the two tumors, about < 5% and 20% respectively. Immunohistochemically, the epithelial element expressed AE1/AE3, CK5, CK7, CK8 and EMA, whereas the spindle component expressed AE1/AE3, CK5, CK7, CK8, vimentin, CD10, CD34, alpha-SMA, MSA, and calponin. Both elements were negative for CK20, TTF-1, desmin, S-100 protein, CD57, GFAP and CD99.</p><p><b>CONCLUSIONS</b>EHT is a benign tumor that occurs predominantly in the lower neck region of young to middle-aged males. Immunohistochemical study revealed myoepithelial differentiation of the spindle cells, suggesting EHT is a mixed tumor composed of epithelial and myoepithelial cells. EHT possibly originates from the remnants of cervical sinus of His, and therefore, may be renamed as branchial anlage mixed tumor.</p>

Desmoplastic small round cell tumor: a clinicopathologic study of 15 cases / 中华病理学杂志

<p><b>OBJECTIVE</b>To study the clinicopathologic features and immunophenotype of desmoplastic small round cell tumor (DSRCT), and to assess the feasibility of reverse transcriptase-polymerase chain reaction (RT-PCR) as a diagnostic adjunct for DSRCT in routine practice.</p><p><b>METHODS</b>The clinical (number = 15), cytologic (number = 1) and histopathologic (number = 14) features of 15 cases of DSRCT were investigated. The immunophenotype was studied by LSAB method using a panel of antibodies. RT-PCR was performed in one case using formalin-fixed, paraffin-embedded tissue for EWS-WT1 fusion gene mRNA.</p><p><b>RESULTS</b>Among the 15 patients studied, 13 were males and 2 were females. Their age ranged from 12 to 38 years (mean age = 23.8 years). Most presented with vague abdominal discomfort, distension or pain, accompanied by nausea, constipation and weight loss. Physical examination showed a palpable abdominal mass with ill-defined borders and tenderness. Ultrasound and computerized tomographic examination revealed single or multiple nodular tumor mass(es) in the peritoneal cavity, measuring 3 cm to 25 cm in greatest diameter (mean tumor diameter = 8.6 cm). Cytologic examination in 1 case showed clusters of small round cells in a hemorrhagic background. The tumor nuclei were hyperchromatic and contained inconspicuous nucleoli. Mitotic figures were readily identified. The cytoplasm however was scant. Histologically, the tumor was composed of small, round, ovoid to spindled cells arranged in nests of various shapes and sizes, embedded in a desmoplastic and focally hyalinized stroma. Immuno- histochemically, all cases showed diffuse and strong staining for AE1/AE3, vimentin, desmin and neuron-specific enolase. Some of them also expressed CAM5.2, epithelial membrane antigen, CD57, chromogranin A, synaptophysin and WT1. They were all negative for myogenin, CK5/6, CD117, calretinin and CD99. RT-PCR successfully amplified the EWS-WT1 chimeric mRNA in 1 case using paraffin-embedded tissue. Subsequent DNA sequencing showed that the gene fusion involved exon 7 of EWS and exon 8 of WT1 genes. The fusion gene contained KTS sequence.</p><p><b>CONCLUSIONS</b>DSRCT is a highly malignant small round cell tumor occurring predominantly in the abdominal or pelvic cavity of young to middle-aged males. It is characterized by multiphenotypic differentiation. The peculiar perinuclear dot-like staining pattern for vimentin and desmin is characteristic for DSRCT. EWS-WT1 fusion transcript can be detected in formalin-fixed, paraffin-embedded tissue by RT-PCR, which may thus serve as a useful diagnostic adjunct for DSRCT.</p>

Malignant granular cell tumor: a clinicopathologic analysis of 10 cases with review of literature / 中华病理学杂志

<p><b>OBJECTIVE</b>To investigate the clinicopathologic features of malignant granular cell tumor (MGCT) and evaluate the histologic criteria for diagnosis of malignancy.</p><p><b>METHODS</b>The clinical and pathologic profiles of 10 MGCT cases were evaluated. Immunohistochemical study was performed on paraffin sections of 9 cases. Electron microscopy was carried out in 3 cases with available fresh or formalin-fixed tissues. The biologic behavior was analyzed with follow-up data.</p><p><b>RESULTS</b>Four patients were males and six were females. Their age ranged from 27 to 73 years (mean = 46 years). The main presenting symptom was a painless nodule or mass located in the subcutis or deep soft tissue. One case had peripheral nerve symptoms. Three of the tumors occurred in the lower extremity, two in the breast, two in the nuchal region, and one each in the chest wall, neck, and peritoneal cavity. The tumor size ranged from 2 to 11 cm (mean size = 4.8 cm). Microscopically, the tumor was composed of nests or sheets of polygonal cells which possessed abundant eosinophilic granular cytoplasm and closely resembled its benign counterpart. After careful assessment, 9 cases exhibited at least 3 of the following suspicious features: enlarged vesicular nuclei with prominent nucleoli, nuclear pleomorphism, high nuclear-to-cytoplasmic ratio, spindling of tumor cells, appreciable mitotic activity, and tumor necrosis. In addition, a hitherto undescribed feature characterized by multinucleated tumor cells was observed in 1 case. The remaining case demonstrated benign-appearing features but behaved in a malignant fashion. Immunohistochemical study showed positive staining for S-100 protein (9/9), neuron specific enolase (9/9) and CD68 (7/9). Electron microscopy demonstrated abundant intracytoplasmic autophagic vacuoles. Follow-up information available in 7 patients revealed local recurrence in 5, metastasis in 4 and tumor-related deaths in 2 patients.</p><p><b>CONCLUSIONS</b>The histologic criteria for malignancy in GCTs established in 1998 by Fanburg-Smith et al. are reproducible in most instances. In exceptional circumstances, however, the diagnosis relies on clinicopathologic correlation. Based on the current study and literature review, a modified criterion of mitotic count (> 5/50 HPF instead of > 2/10 HPF) is recommended. Wide local excision with regional lymph node dissection remains the mainstay of treatment. Chemotherapy and radiotherapy however have not been shown to significantly improve the clinical course of the disease. The morphologic spectrum of MGCT also includes a rare multinucleated variant.</p>