Answer: C. Malakoplakia

Histological Description: Focally residual necrotic seminiferous tubules are visible with associated marked acute inflammation. Adjacent to the extensive necrosis, are numerous cells with abundant eosinophilic cytoplasm with round nuclei with small but visible nucleoli. Within many of these cells are light amphophilic inclusions, some of which have the appearance of a target with a central dark round bulls-eye surrounded but a white circle. Admixed are numerous plasma cells, lymphocytes, neutrophils, and fibrosis.

Discussion: The key to the diagnosis in the case rests on recognizing that the overall process is inflammatory as opposed to neoplastic. Whereas seminomas typically have a lymphocytic infiltrate and can have a prominent associated granulomatous component, they lack admixed neutrophils. IgG 4 related disease is not well recognized in the testis and also would lack prominent neutrophils and necrosis. The tip to recognizing malacoplakia is noting that there are scattered bluish inclusions in many of the histiocytes and then searching for more classic small basophilic extracytoplasmic or intracytoplasmic calculopherules resembling bulls-eyes on a target (Michaelis-Gutmann bodies). Although typically these stains are usually not necessary, Michaelis-Gutmann bodies are positive for calcium stains (von Kossa) and iron stains (Prussian blue). Cells are positive for histiocyte markers (i.e. CD68) and negative for keratins. Treatment is primarily based on controlling the urinary tract infections, which stabilizes the disease. Adding bethanechol, a cholinergic agent thought to increase the intracellular cyclic guanosine monophosphate levels considered to be the defect-causing macrophage dysfunction, may also be useful. Surgery may be necessary, as in this case, if malacoplakia makes a mass mimicking a neoplasm or if it results in local morbidity that cannot be controlled with antibiotics.