Multicentric Reticulohistiocytosis—Histopathologic Spectrum in Indian Patients

Multicentric reticulohistiocytosis (MRH) is a rare histiocytosis, characterized by polyarthritis and multiple papulonodular lesions in the skin, mucosa, and visceral organs. It has a robust association with autoimmune diseases and malignancies. We studied histopathological features of 4 cases of MRH over a period of 11 years (2012-2023). The mean age was 48 years with no gender predilection. All patients had papulonodular skin lesions distributed over dorsum of finger, scalp, pinna, hands, elbows, and back. Associated conditions include arthritis in 2 cases and malignancy in 2 cases. All biopsies showed sheets of histiocytes, the morphology of which varied from having dense eosinophilic glassy appearing cytoplasm to abundant vacuolated cytoplasm. Good clinicopathologic correlation is necessary to make a diagnosis; however, it is not always possible to establish diagnosis at the time of biopsy. Follow-up diagnosis of malignancy led to the diagnosis in 2 cases. This small, yet insightful, case series emphasizes the need for good clinicopathologic correlation regardless of histiocyte morphology when MRH is suspected.