Microscopic description:

Lipid-laden macrophages, plasma cells and lymphocytes

The bladder wall has a localized collection of foamy histiocytes which are negative for AE1/AE3 (positive in urothelial epithelium) and positive for macrophage marker (CD68). These findings are compatible with the diagnosis of a xanthoma.

Discussion:

Rare (<50 cases reported in bladder) benign inflammatory disorder characterized by lipid-laden macrophages

Associated with xanthogranulomatous pyelonephritis, urachal adenomas, inflammatory bowel disease

Lipid-laden macrophages, plasma cells and lymphocytes

May have some Touton-type giant cells

Like malakoplakia but without Michaelis-Gutmann bodies

IHC: Positive:CD68, CD163; Negative: CK

Differential Diagnosis:

  • Malakoplakia: Foamy epithelioid histiocytes with PAS+ granular eosinophilic cytoplasm in lamina propria, some lymphocytes and occasional giant cells. Histiocytes have increased number of phagosomes containing non-digested bacteria (usually E. coli or Proteus), contain Michaelis-Gutmann bodies (iron containing, cytoplasmic laminated mineralized concretions)
  • Urothelial carcinoma: Nested variant demonstrates bland, low-grade cytology and can be confused with Xanthoma

References:

Bates, A. W., Fegan, A. W., & Baithun, S. I. (1998). Xanthogranulomatous cystitis associated with malignant neoplasms of the bladder. Histopathology, 33(3), 212–215. https://doi.org/10.1046/j.1365-2559.1998.00468.x

Goel, R., Kadam, G., Devra, A., Patel, S., & Modi, P. (2007). Xanthogranulomatous cystitis. International urology and nephrology, 39(2), 477–478. https://doi.org/10.1007/s11255-006-9059-8

Goel, R., Kadam, G., Devra, A., Patel, S., & Modi, P. (2007). Xanthogranulomatous cystitis. International urology and nephrology, 39(2), 477–478. https://doi.org/10.1007/s11255-006-9059-8

CASE IMAGES