Desmoplastic spitz nevus: report of a case and review of the literature

Desmoplastic spitz nevus (DSN) is an uncommon melanocytic lesion. The histologic features of this benign tumour may mimic those of certain benign (dermatofibroma and desmoplastic cellular blue nevus) or malignant (metastatic carcinoma and malignant melanoma) neoplasms. We report the case of a male with a DSN, and also review the clinical characteristics, histologic features and differential diagnosis of this extremely rare lesion. The lesion is identified as an asymptomatic reddish-brown dome-shaped papule on the forearm. Microscopic examination showed a symmetric lesion in the dermis. The neoplastic cells were large and epithelioid-shaped, and were either isolated as individual cells or arranged in small nests in a paucicellular hyalinized stroma. Nuclei were large and vesicular with small nucleoli and no mitoses. Diffuse expression of S100 and the absence of staining with antibodies to melan-A and HMB45 was observed. A diagnosis of DSN with free margins was made. The histologic presentation of this benign lesion mimics both benign and malignant neoplasms. The immunohistochemical profile (S100 positive, HMB-45 negative and cytokeratin negative) may be helpful to differentiate it from other lesions.

Myxoid tumor of soft tissue

Focal myxoid change is a well-recognised feature of synovial sarcoma, but the presence of a predominantly myxoid stroma is rare. We describe a new case of myxoid synovial sarcoma in which marked myxoid change initially obscured the diagnosis leading to confusion with malignant peripheral nerve sheath tumor. The patient was a 16 year old man who presented with a left dorsal foot tumor. The diagnosis of synovial sarcoma was suspected on histological and immunohistochemical studies and confirmed with cytogenetic analysis. Recognition of this rare histologic variant of synovial sarcoma is important because it can easily be mistaken for other myxoid spindle cell neoplasms, potentially resulting in suboptimal therapy.

Micropapillary transitional cell carcinoma of the urinary bladder: report of two cases

Micropapillary carcinoma is an uncommon variant of urothelial carcinoma with apparent high metastatic potential. The reported cases in the literature were associated with high grade and stage of disease at presentation and a poor prognosis. Micropapillary carcinoma is considered a tumor with an aggressive behavior, even though the morphology may be deceptive. The presence of a micropapillary carcinoma component in bladder biopsies should alert the urologists to the potential of higher stage disease and deep biopsies should be obtained. Two cases of micropapillary carcinoma of the urinary bladder were presented. A 71-year-old woman and a 68-year-old man presented with urinary symptoms. Cystoscopy revealed a papillary tumor on the bladder wall in both cases. Pathologic examination of transurethral resection specimen showed an invasive micropapillary carcinoma; small solid nests lying in small clear spaces that were not stained with antibody CD34. Thus, the lacunar histological pattern did not appear to represent invasion of vascular spaces. Only one case showed an association with urothelial carcinoma. No case showed muscle invasion. No recurrence or metastasis were observed after the initial diagnosis in the two cases.