Unabridged Histoplasmosis Myositis: Unsolved Dissemination with Diagnostic Challenge

Histoplasmosis occurs predominantly in immunocompromised hosts and typically presents with mild constitutional symptoms, weight loss, weakness, fatigability, hepatosplenomegaly, and lymphadenopathy. The diagnosis is generally delayed and is based upon isolating the organism in blood cultures or by identifying intracellular organisms in tissues. Disseminated Histoplasmosis is well described in HIV patients but Histoplasmosis myositis is a rare manifestation and has not been reported in seronegative patients till date. We here address a case of a pharmacologically immunosuppressed patient with extensive Histoplasmosis myositis invading almost all the skeletal muscles of body (including plantar foot muscles) with no evidence of dissemination to other organ-systems. Clinical examination and investigations co-related with infiltrative muscle disease and skeletal muscle biopsy revealed Histoplasma capsulatum. This patient illustrates a distinctive clinical presentation of fungal infection with subtle constitutional symptoms and isolated muscle weakness which added to the diagnostic challenge. Hence, differential diagnosis of fungal infection must always be considered as a cause of myopathy in any pharmacologically immunosuppressed patient.