Background/Purpose

Multicentric Reticulohistiocytosis (MRH) is a rare systemic inflammatory disease with skin nodules and arthritis. On skin or joint biopsy the hallmark is the presence of multinucleated giant cells and histiocytes with a ground glass appearance of the cytoplasm secondary to lipid inclusions. In the past solitary or multiple cutaneous reticulohistiocytoma without joint involvement were thought to be a separate entity because it only affects the skin, albeit the histopathology is identical. Due to the rarity of the disease little is known about pathophysiology or treatment. Anecdotal reports suggest that the use of TNF inhibitors and bisphosphonates may be beneficial. We wished to review the combined experience of this rare condition at a tertiary care institution.

Methods After obtaining IRB approval, we searched the electronic medical records at the University of Iowa Hospital and Clinics (UIHC) to identify all patients with MRH or cutaneous reticulohistiocytoma seen between January 2000 and December 2013. The aims of this retrospective study are to describe the different treatments and outcomes and concomitant diagnoses in patients with MRH/cutaneous reticulohistiocytoma with or without joint involvement.

Results

We have identified 16 patients of which 4 had both skin and joint involvement and 12 cases with cutaneous  involvement only that were diagnosed and treated at UIHC. All cases had a skin biopsy consistent with non-Langerhans reticulohistiocytosis. The age of patients with MRH ranged from 48-66 years old. Hands, wrists and knees were the most commonly affected joints. Treatments varied from intravenous infusions of zoledronic acid to TNF-inhibitors (adalimumab and etanercept) with varying responses. Two patients were treated with cyclophosphamide with improvement of disease. None of the patients were diagnosed with a malignancy.

Conclusion

Multicentric reticulohistiocytosis and cutaneous reticulohistiocytoma share identical histopathology but have different distribution and organ involvement. The pathogenesis and mechanism for different organ distribution of this systemic inflammatory disease is unknown. We report here the largest case series to date (16 cases) from a single academic institution in the last 13 years. It seems that MRH includes a wide spectrum ranging from no joint involvement to severe destructive arthritis. Follow up of patients with solitary and multiple cutaneous reticulohistiocytoma is warranted as joint involvement may develop with time.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/multicentric-reticulohistiocytosis-case-series-from-a-tertiary-care-center/