Epithelioid sarcoma of the right ilium mimicking sacroiliitis.

Epithelioid sarcoma represents less than 1% of soft tissue sarcomas and has a high recurrence rate and strong ability to invade the regional lymphatic pathways. Classic epithelioid sarcoma has a predilection for young men and usually affects the distal extremities, while the proximal-type is characterized by different histological features and most commonly occurs in the proximal part of the extremities, trunk and pelvis. Intraosseous tumor development is rare.

Nephrogenic adenoma: an immunohistochemical analysis using biotin-free methods.

Nephrogenic adenoma (NA) has been considered as a metaplastic process of the urothelium. It has been suggested that this lesion is of renal tubular cell origin or differentiation. Immunohistochemical studies of NA emphasize its staining with α-methylacyl-coenzyme A racemase (AMACR), and prostatic adenocarcinoma may be a possible differential diagnosis.