title: Superficial paramucosal clear cell sarcoma of the soft parts resembling melanoma in a 13-year-old boy.
abstract: Clear cell sarcoma (CCS) of tendons and aponeuroses, also known as melanoma of soft parts, represents an aggressive rare malignancy that is characterized by a nested or fascicular pattern of spindled cells and a pathognomonic reciprocal translocation, t(12;22)(q13;q12), that results in the fusion of EWSR1 and ATF1 genes. Numerous recent studies have recognized the importance of a cutaneous CCS variant that can mimic a broad spectrum of entities, including spindle cell melanoma, spindle cell squamous carcinoma, cutaneous leiomyosarcoma and atypical fibroxanthoma. We report a case of a 13-year-old boy with cutaneous CCS who presented with a few months history of an asymptomatic papule on the lower lip that was suggestive of a mucocele. Biopsy of the lesion showed a wedge shaped neoplasm arranged in nests and fascicles of epithelioid- to oval-shaped cells with pale cytoplasm, open chromatin and prominent nucleolus. The superficial component was closely opposed to the basal epithelium resembling the junctional nests of a melanocytic neoplasm. The process extended into and involved the striated muscle of the lip. The cells expressed S-100, CD99 and synaptophysin by immunohistochemistry, and there was focal HMB-45 and microphthalmia transcription factor (MiTF) positivity as well. Fluorescence in situ hybridization confirmed the presence of the t(12;22) (ESWR1-ATF1) translocation.
authors.affiliation: Department of Dermatology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Sidiropoulos
authors.forename: Klaus
authors.initials: K
authors.lastname: Busam
authors.forename: Joan
authors.initials: J
authors.lastname: Guitart
authors.forename: William B
authors.initials: WB
authors.lastname: Laskin
authors.forename: Annette M
authors.initials: AM
authors.lastname: Wagner
authors.forename: Pedram
authors.initials: P
authors.lastname: Gerami
mesh_terms: D000293:Adolescent; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008048:Lip Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D018227:Sarcoma, Clear Cell / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
chemical_list: C560860:EWSR1-ATF1 fusion protein, human; D015514:Oncogene Proteins, Fusion