Histoplasmosis Masquerading as a Rheumatoid Nodule in an Immunocompromised Host: A Case Report.

Abstract

Articular infection has infrequently been described as being caused by Histoplasma capsulatum . We report a case of a periarticular shoulder mass due to an H. capsulatum infection that mimicked the clinical presentation of a rheumatoid nodule. This case highlights the importance of microbiologic examination when an inflammatory soft-tissue mass is identified, particularly in an immunocompromised host who may not present with classic signs or symptoms of infection. The patient was informed that data concerning the case would be submitted for publication, and he provided consent. A sixty-three-year-old man with rheumatoid arthritis presented with a six-month history of pain and swelling of the left shoulder. Medications included methotrexate (12.5 mg weekly), leflunomide (30 mg daily), and prednisone (5 mg daily). He had no history of tumor necrosis factor antagonist therapy. A review of systems was noteworthy for fatigue, joint pain, stiffness, and swelling; he denied chest pain, cough, shortness of breath, fevers, chills, or night sweats. Physical examination revealed a temperature of 36.6°C and a nontender mass over the anterior aspect of the left shoulder; there was no overlying warmth or erythema. The peripheral blood leukocyte count was normal at 8800 cells/mm3 with a polymorphonuclear (PMN) predominance (83%); the remainder of the complete blood-cell count and comprehensive metabolic panel was within normal limits. Erythrocyte sedimentation rate (ESR) was elevated at 65 mm/h, and the C-reactive protein (CRP) level was elevated at 36.5 mg/L. Magnetic resonance imaging (MRI) of the left shoulder following intravenous gadolinium contrast administration revealed an enhancing mass involving the rotator cuff musculature, soft tissue, and adipose tissue. The mass was predominantly extra-articular, but intra-articular enhancement was also noted. The long head of the biceps tendon was completely torn, and there was circumferential labral tearing and degeneration (Figs. 1-A through 1-D). Positron emission tomography revealed markedly increased …