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
A biopsy specimen obtained from a large papule on the forearm showed a normal epidermis with small amounts of basophilic deposits splitting the collagen bundles throughout the papillary dermis and the upper reticular dermis. A slight proliferation of fibroblast and thin-walled vessels surrounded by lymphocytes was also seen. Histopathological examination of a biopsy specimen from a nodule on the left knee disclosed a deep and diffuse proliferation of randomly arranged delicate spindle cells embedded in an abundant myxoid stroma involving the subcutaneous tissue (Figure 2). Only focal involvement of the superficial and reticular dermis was noted. Scattered epithelioid ganglionlike mononuclear cells with large nuclei and prominent nucleoli were also noted within the myxoid areas (Figure 3). Occasional mitotic figures were also present. Both sections stained strongly with Alcian blue (pH 2.5), confirming the mucin deposition. Immunohistochemical staining revealed the spindle cells to be positive for vimentin and weakly positive for desmin. Stains for cytokeratin, CD34, smooth muscle actin, muscle-specific actin, and epithelial membrane antigen were negative. A close and periodical follow-up was recommended. During the following months, the lesions progressively and spontaneously regressed, and after 8 months no clinical lesions were present.
Autoinvolutive Papules and Nodules in a Child—Diagnosis. Arch Dermatol. 2012;148(6):755-760. doi:10.1001/archderm.148.6.756-d