Acral Persistent Papular Mucinosis in the United States: Case Series and Literature Review.

Background: Acral persistent papular mucinosis (APPM) is a localized variant of lichen myxedematosus (LM) characterized by asymptomatic, flesh-colored papules primarily distributed on the hands and forearms. This chronic dermatosis, distinct from generalized mucinosis due to its lack of systemic involvement, remains underreported in medical literature. Objective: In this study, we present two cases of APPM to the limited pool of documented cases in the United States, highlighting its emerging recognition. Methods: This is a case series of two patients presenting with asymptomatic papular eruptions on the hands and wrists, consistent with the typical presentation of APPM. Diagnostic confirmation via biopsy revealed focal cutaneous mucinosis. Comprehensive laboratory evaluations, including serum and urine protein electrophoresis, showed no evidence of underlying gammopathy in either patient. Results: Treatment modalities for APPM are limited and often ineffective. Unlike other forms of LM, APPM features are confined to skin lesions, posing primarily as a cosmetic concern with a favorable prognosis. Accurate diagnosis of this localized LM is crucial to differentiate it from the more severe, generalized form, scleromyxedema, which can have organ involvement and may become fatal. Notably, while spontaneous resolution is reported in LM, including discrete papular mucinosis, APPM typically persists without resolution even after extended follow-up. Conclusions: These cases underscore the importance of recognizing APPM and advocating for broader awareness and exploration of its clinical variability, etiology, and management strategies. With increasing recognition, the understanding of APPM can be enhanced, paving the way for optimized management and improved outcomes for affected individuals.