Crystal storing histiocytosis presenting as a temporal lobe mass lesion.

BACKGROUND: Crystal storing histiocytosis (CSH) is a disorder characterized by local or diffuse infiltration of histiocytes containing crystalline inclusions most commonly of immunoglobulin light chain. Involvement of the central nervous system is extremely rare. CSH may be misdiagnosed as an infection or tumor. In patients with involvement of other organs, it is frequently associated with lymphoplasmacytic diseases. CASE DESCRIPTION: A 20-year-old female was evaluated for 2 weeks of progressively worsening headaches. At presentation, she had no history of fevers but reported a sore throat without cough 3-4 days prior. Her past medical history was unremarkable. She denied intravenous drug use or sexually transmitted diseases but lived with an individual with a history of fungal meningitis. On examination she was afebrile, alert, and oriented with a blood pressure of 110/70 mmHg. She had no adenopathy or neurological deficits. Her white blood cell count was minimally elevated. 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 an infectious or neoplastic process. Cultures for infectious agents were negative. The biopsy showed CSH. Postoperatively and at 1 month follow up, she was neurologically intact. CONCLUSION: Radiographically and intraoperatively, CSH may mimic an infectious process or neoplasm. Its recognition is critical to facilitate appropriate therapy and prompt screening for an occult lymphoplasmacytic neoplasm, plasma cell dyscrasia or other underlying disease.