Samuel Goodloe

Solitary Fibrous Tumor with Entrapment of Minor Salivary Gland Tissue: An Unusual Presentation That Requires Exclusion of Pleomorphic Adenoma

We report two unusual cases of solitary fibrous tumor (SFT) of minor salivary glands that microscopically mimicked pleomorphic adenoma. One of these lesions presented in the retromolar region and the other in the buccal mucosa. The microscopic features of these two tumors and their intimate relationship with regional mucous minor salivary glands posed a diagnostic challenge. Awareness of the morphological diversity of SFT coupled to a judicious use of appropriate immunohistochemical probes should prove valuable to accurately segregate SFT from pleomorphic adenoma.

Giant clear cell hidradenoma of the knee

Hidradenomas, also referred to as nodular hidradenomas or clear cell hidradenomas (CCH), are benign cutaneous eccrine tumors usually 2–3 cm in dimension. Hidradenomas are relatively common; however, giant forms are rare. We report a case of an 8.0 × 6.0 × 3.0 cm clear cell hidradenoma of the left knee in a 43‐year‐old man. The tumor was mobile, located above the patellar tendon and was without bony involvement on imaging studies. Grossly, the resected tumor was unencapsulated and tan, with a solid and cystic cut surface showing papillary excrescences on the cyst wall. Microscopically, the tumor cells showed an infiltrative growth pattern at the periphery, however, the tumor cytology was bland and no necrosis or mitoses were identified. The overlying dermis contained hemosiderin pigment deposition and infiltration with eosinophils. Immunohistochemically, tumor cells were positive for cytokeratin, CAM5.2, p53, carcino‐embryonic antigen (CEA) and epithelial membrane antigen (EMA), and negative for CD10 and Ki‐67. The cytological features of hidradenomas can present diagnostic challenges, as other ‘clear cell’ tumors such as metastatic renal cell carcinoma should be considered. Immunohistochemical studies and differential diagnoses are discussed.

Immunohistochemical Studies of Cell Cycle-associated Proteins in a Case of Giant Cell Granuloma of Mandible

Central Giant Cell Granuloma (CGCG) is a localized benign osteolytic lesion with variably aggressive nature. Due to the rarity of this disease, only a few studies with a limited number of cases have been reported, the results of which are controversial. Hence, there is not much data on the possible mechanisms underlying its aggressive biological behavior. In our study, immunohistochemistry was performed on a 50-year old female diagnosed with a giant cell granuloma of the mandible. We attempted to examine the expression profile and cellular distribution of cell cycle-associated proteins: cyclin D1, p53, PCNA, MIB-1 and facor XIIIa. Our results demonstrated that high-level expression of cyclin D1 was predominant in the nuclei of 85% of giant cells whereas cyclin D1 staining was noticed in only 20% of mononuclear cells. Expression of PCNA and MIB-1, on the other hand, was observed in 70% and 40% of mononuclear cells respectively, with less than 10% positive staining present in the giant cells. P53 protein did not appear to be overexpressed in either mononuclear or giant cells, and factor XIIIa was detected only in isolated stromal fibroblasts. These results support the hypothesis that over-expression of cyclin D1 in giant cells may play a role in the pathogenesis of CGCG, and the differential expression pattern of cyclin D1 and PCNA may be involved in the formation of multinucleated giant cells. [N A J Med Sci. 2009;2(2):48-50.]