title: Bilateral multifocal upper extremity atypical granular cell tumors presenting as long-standing right wrist and left hand masses in a 15-year-old African-American female.
abstract: Granular cell tumor (GrCT) is a benign nerve sheath tumor. Atypical and malignant variants of GrCT are rare but have been well described. We report a case of multifocal symmetric atypical GrCT in the bilateral hand/wrists of a 15-year-old African-American female. The initial clinical impression for both masses was favored to be ganglion cysts. Ultrasound findings of both masses revealed hypoechoic soft tissue lesions with some internal echogenicity favoring complex cysts. On excision, both masses were histologically circumscribed, lobulated and attached to tendon. Large epithelioid cells with abundant granular eosinophilic cytoplasm arranged in syncytial cords and trabeculae percolated through collagen. Many cells had pleomorphism and/or prominent nucleoli. Mitotic figures, spindling, high nuclear-to-cytoplasmic ratio and necrosis were absent. Both masses showed diffuse S100 protein but negative desmin and pancytokeratin expression. Ki-67 index was 1% to 2%. p53 was positive in 5% to 10% of nuclei. Both masses met criteria for atypical (but not malignant) GrCT. Our case shows that atypical GrCT may be not only multifocal but also symmetric. We speculate that migration of defective neural crest stem cells along both upper limb buds during embryogenesis may have allowed these essentially identical tumors to arise in similar locations bilaterally simultaneously.
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
authors.forename: Michael
authors.identifier: http://orcid.org/0000-0002-3572-0505
authors.initials: M
authors.lastname: R DeWall
authors.affiliation: Department of Orthopedic Surgery, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
authors.forename: Corey O
authors.initials: CO
authors.lastname: Montgomery
authors.affiliation: Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
authors.forename: Jerad M
authors.identifier: http://orcid.org/0000-0001-7397-2159
authors.initials: JM
authors.lastname: Gardner
mesh_terms: D000293:Adolescent; D005260:Female; D006801:Humans; D019394:Ki-67 Antigen / Q000378:metabolism*; D008938:Mitosis; D009363:Neoplasm Proteins / Q000378:metabolism*; D018317:Nerve Sheath Neoplasms / Q000378:metabolism / Q000473:pathology; D009418:S100 Proteins / Q000378:metabolism*; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology; D014953:Wrist / Q000473:pathology*
chemical_list: D019394:Ki-67 Antigen; D009363:Neoplasm Proteins; D009418:S100 Proteins
keywords: atypical granular cell tumor; bilateral granular cell tumor; granular cell tumor; nerve sheath tumor; symmetric neoplasm