A cutaneous nodule revealing Münchmeyer's disease.

Münchmeyer's disease, also known as fibrodysplasia ossificans progressiva, is an extremely rare congenital condition affecting the musculoskeletal system, occurring in approximately 1 in 2 million people. We report the case of a 13-month-old male toddler who presented with dorsal cutaneous nodules. Examination revealed a firm, immobile nodule and congenital hallux valgus with microdactyly. Imaging studies showed ossifications of the subcutaneous tissues, and genetic testing confirmed a mutation in the ACVR1 gene, leading to the diagnosis of Münchmeyer's disease. This disabling, progressive condition is characterized by extraskeletal ossification and congenital big toe malformations. The precocity of the diagnosis in this case is noteworthy, as Münchmeyer's disease is often misdiagnosed, leading to significant delays and complications. Awareness of this rare condition is important for dermatologists to avoid missed or delayed diagnoses, as early recognition and appropriate management are crucial.