Question:

A 49-year-old male presents for evaluation of several lesions on his hands pictured below that have been increasing in number over the past few months. Which of the following is most commonly associated with this condition?

Answers:

A. Malignancy

B. Erosive arthropathy

C. Tuberculosis

D. Autoimmune disorder

E. Systemic vasculitis 

Rationale:

Multicentric reticulohistiocytosis is an inflammatory disorder affecting the skin, joints, and mucous membranes. Cutaneous findings typically include a symmetric eruption of round, red/brown papules, and nodules; the characteristic coral bead appearance periungually is seen in the photograph above. On histology, histiocytes with a ground-glass appearance are seen. Multicentric reticulohistiocytosis is associated with malignancy in up to a quarter of patients. Other reported associations include mycobacterial infections and autoimmune conditions such as systemic lupus erythematosus. 

Correct answer: B. Erosive arthropathy 

A major component of multicentric reticulocytosis is an erosive polyarthritis involving multiple joints, most commonly the interphalangeal joints in the hands. In a recent case series of 24 patients seen over a 37-year span at a single center, 92% of individuals were found to have arthralgias. Joint symptoms typically develop before the skin lesions and may precede cutaneous findings by years. 

Incorrect answers: A, C, D, E

Although all of these choices have been associated with multicentric reticulohistiocytosis, erosive polyarthritis is most common. However, the risk of underlying malignancy should not be underscored as up to a quarter of patients have been found to have malignancy, most commonly hematologic, gastric, or breast. Therefore, extensive malignancy screening should be performed. 

Additional reading at Fitzpatrick's Dermatology Chapter 117: Histiocytosis 

Sanchez-Alvarez C, Sandhu AS, Crowson CS, Wetter DA, McKenzie GA, Lehman JS, Makol A. Multicentric reticulohistiocytosis: the Mayo Clinic experience (1980-2017). Rheumatology (Oxford). 2020 Aug 1;59(8):1898-1905. doi: 10.1093/rheumatology/kez555. PMID: 31742640.