Trauma-Induced Cutaneous Focal Mucinosis of the Mammary Areola: An Unusual Presentation

Cutaneous focal mucinosis (CFM) is a localized form of cutaneous dermal mucinosis clinically presenting as an asymptomatic skin-colored papule or nodule. The etiopathogenesis of CFM is unclear, but it is thought to represent a reactive lesion. Although trauma has been suspected as a triggering factor, it has never been proven in cases of CFM. We report 2 male patients with trauma-induced CFM arising at the mammary areola, which is an unusual site for CFM. Both male patients presented with a solitary nodular lesion of up to 2 cm in diameter at the right areola. Histology was characterized by circumscribed abundant dermal mucin deposits in a polylobulated pattern without an increased number of fibroblasts or capillaries and with absence of an inflammatory infiltrate. Alcian blue stain at pH 2.5 highlighted the mucin deposits. Immunohistochemistry showed partial expression of FXIIIa by 30% of the stromal cells, but no reactivity for CD34, smooth muscle actin, desmin, CD68 and S-100. A history of trauma (laser-based epilation, piercing) preceded the development of CFM in both patients. Surgical excision resulted in complete remission without recurrence. Follow-up in both our patients did not reveal recurrences. CFM has to be distinguished from benign and malignant myxoid neoplasms.