Crystal storing histiocytosis presenting as a temporal lobe mass lesion
A 20-year-old female was evaluated at an ambulatory care center for headaches that had become progressively worse over the prior 2 weeks. She had been treated for mycoplasma infection by a primary care physician. At presentation, the headaches were reportedly severe. The patient had no history of fevers but reported a sore throat 3-4 days prior without a cough or other discomfort. Her past medical history had no notable illnesses. Regarding her social history, she lived on a farm with a friend who had been treated for fungal meningitis in the past. No tobacco, alcohol, or intravenous drug use was admitted. She denied exposure or prior treatment for sexually transmitted diseases. She had no significant past medical history. On examination she was afebrile with a blood pressure of 110/70 mmHg. She was alert and oriented with no adenopathy. A complete blood count revealed a white blood cell (WBC) of 12.4 (4.2-9.1 thousand/microliter), 87% neutrophils with no bands. Serology was negative for mycoplasma and HIV-1. Her neurological exam was normal. Magnetic resonance imaging revealed a 3.5 × 1.3 × 1.9 cm contrast enhancing lesion of the left temporal lobe with a mild midline shift []. Evaluation by multiple specialists suggested a differential diagnosis of a noninfectious process (favored) neoplastic process or infection. She was treated with vancomycin 1.25 g IV per 12 h and meropenem 2 g IV q 8 h and decadron.\nThe mass was resected and aerobic, anaerobic, mycobacterial, and fungal cultures were taken. Anaerobic and aerobic cultures as well as gram, modified acid fast bacillus, and fungal stains were negative. Brain tissue polymerase chain reaction analysis at the state Department of Public Health laboratory public was negative for infectious agents. Due to initial uncertainty about the diagnosis and anticipation of the need for multiple studies in the laboratories, she was postoperatively treated with vancomycin IV for 10 days. Postoperative scans revealed gross total resection. On postoperative day 1 and 30 she was neurologically intact.\nThe sections revealed a fibrotic lesion with an extensive chronic inflammatory infiltrate of CD138-immunoreactive plasma cells, CD68-immunoreactive macrophages and monocytes and S100-immunoreactive histiocytes []. Plasma cells showed IgG, IgM, predominantly lambda but also some kappa immunoreactivity. There were numerous periodic acid-Schiff (PAS) staining rhomboid crystals and granular material that was predominantly intracellular but also extracellular []. No polarizable material was found. Special stains for bacteria including Nocardia and Mycobacteria were negative. The Grocott's Methenamine Silver GMS stains revealed no fungal organisms. The Masson stain demonstrated extensive dense collagen deposition but no encysted amoeba. There was no Congo red staining apple green birefringent polarizable material. There were no giant cells, viral inclusions, Herpes Simple ×1 or 2, cytomegalovirus, Epstein–Barr virus, or Toxoplasma immunoreactivity. There was no Alk-1 but scattered spindle cells and blood vessels show SMA immunoreactivity. To evaluate whether immunoglobulin expression was predominantly one type, additional immunoflourescence and in situ hybridization were performed. These demonstrated overwhelmingly lambda light chain restriction []. Electron microscopy revealed numerous intracellular but also extracellular rhomboid and diamond-shaped crystals []. Collectively the findings of histiocytes with intracellular rhomboid and diamond-shaped crystals showing light chain and exclusion of other neoplastic and infectious processes were considered consistent with CSH, light chain subtype.