Multicentric reticulohistiocytosis masquerading as cutaneous connective tissue disease.

Multicentric reticulohistiocytosis (MRH) is a rare type of non-Langerhans cell histiocytosis characterized by coral-toned papules with predilection for dorsal surfaces in addition to severe arthropathy. It sometimes proves difficult to differentiate these joint and skin findings clinically from certain rheumatologic diseases, primarily dermatomyositis. Herein, we present an 82-year-old woman who presented with the clinical findings described above and was subsequently diagnosed with MRH after biopsy and review of relevant clinical history. Because about 25% of patients diagnosed with MRH have an underlying occult malignancy, our patient underwent a complete malignancy workup that was negative. She was treated with systemic corticosteroids and methotrexate, which resulted in an improvement of the arthritis and constitutional symptoms. This case demonstrates that in patients with both rheumatologic and dermatologic symptoms, particularly on acral surfaces, MRH must be a diagnostic consideration. Identifying this disease early in its course can prevent negative consequences for the patients, specifically arthritis mutilans and upper airway involvement.