Cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma: a rare occurrence and potential diagnostic pitfall.
A case of cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma is described. The patient was a 60-year-old man who presented with a painless nodule on his chest. Thorough clinical examination did not reveal any evidence of tumor elsewhere. A punch biopsy was performed which showed a benign spindle cell neoplasm with focal cellular pleomorphism that had smooth muscle differentiation and was clearly originating from the arrector pili muscle, consistent with a cutaneous symplastic pilar leiomyoma. Immunohistochemical studies were performed and the tumor cells were strongly positive for smooth muscle actin (SMA) and desmin. Given the clinical information of a mass on the chest, clinical evaluation was recommended and a re-excision was performed. Histologically, the re-excision showed two distinct populations of cells. The upper portion of the tumor mirrored the initial biopsy; however, the base of the tumor showed hypercellular areas composed of spindle cells with marked pleomorphism and increased number of mitoses. The diagnosis of a cutaneous leiomyosarcoma originating in a symplastic pilar leiomyoma was given. This is the first report of this association of such occurrence reported in the literature.
Department of Dermatopathology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
Mark E
ME
Fons
Thomas
T
Bachhuber
Jose A
JA
Plaza
D006801:Humans; D007889:Leiomyoma / Q000473:pathology*; D007890:Leiomyosarcoma / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009378:Neoplasms, Multiple Primary / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology*