Sarcoidosis and psoriasis: a case series and review of the literature exploring co-incidence vs coincidence.

IMPORTANCE

Sarcoidosis is a chronic multisystem disorder characterized by the formation of noncaseating epithelioid cell granulomas affecting multiple organ systems. The role of the type 1 helper T (T(H)1) cell in sarcoidal granuloma formation has been well documented, and the T(H)17 pathway in sarcoidosis is just now being investigated. T(H)17 cells are also known to involved in the pathogenesis of psoriasis, and the coexistence of sarcoidosis and psoriasis is mechanistically plausible based on potential shared underlying immunologic pathways.

OBSERVATIONS: We report a case series of 7 patients with sarcoidosis and psoriasis vulgaris. All patients had psoriasis ranging from limited disease to involvement of 30% of their body surface area and had evidence of pulmonary sarcoidosis. Three of these patients also had cutaneous sarcoidosis, and 1 of these patients had evidence of both psoriasis and sarcoidosis in the same cutaneous specimen.

CONCLUSIONS AND RELEVANCE: We report a case series of concomitant sarcoidosis and psoriasis, suggesting that common pathogenesis involving the T(H)1 and T(H)17 pathways may be responsible for this disease association. Although additional data are needed to clarify this association, this observation may lead to important understanding of the pathophysiologic and therapeutic management in these disorders.