SECTION EDITOR: MARY S. STONE, MD; ASSISTANT SECTION EDITORS: SOON BAHRAMI, MD; CARRIE ANN R. CUSACK, MD; SENAIT W. DYSON, MD; MOLLY A. HINSHAW, MD; ARNI K. KRISTJANSSON, MD
Histopathologic examination revealed groups of spindle cells arranged in fascicles that were oriented parallel to the epidermis. Thick collagen bundles were noted between the fascicles. The neoplasm was limited to the reticular dermis, and there was no involvement of the adnexal structures.
Dermatomyofibroma is an uncommon, benign, plaquelike proliferation of fibroblasts and myofibroblasts that was originally recognized by Kamino et al.1 It predominantly affects young women (mean age at onset, 30 years); however, the lesions have been documented to a lesser extent in males, primarily before the onset of puberty.2,3 Dermatomyofibromas typically manifest as asymptomatic, solitary, relatively well-circumscribed plaques or nodules that may be skin-colored, hypopigmented, or hyperpigmented and are usually 1 to 2 cm in diameter.1,3,4 The lesions, which are slow growing, are predominantly located on the shoulder, upper arm area, and neck, with less frequent appearances on the axilla, thighs, chest wall, back, and abdominal wall.1,2,4
Firm Nodule on the Shoulder —Diagnosis. Arch Dermatol. 2012;148(1):113-118. doi:10.1001/archderm.148.1.114-c