title: Subcutaneous melanocytoma mimicking a lipoma: a rare presentation of a rare neoplasm with histological, immunohistochemical, cytogenetic and molecular characterization.
abstract: Melanocytoma are the melanocytic tumors originating from leptomeningeal melanocytes. Melanocytomas are commonly seen in the central nervous system (CNS) and are often associated with neurocutaneous melanosis (NCM). However, simultaneous presentation of intra-axial and extracranial melanocytoma is a very rare event. Here, we report a unique case of 21-year-old male with intermediate-grade subcutaneous (SC) melanocytoma, mimicking lipoma, occurred synchronously with an intracranial melanocytoma, not associated with NCM. A 21-year-old Caucasian male presented to the emergency department (ED) with severe vertigo and vomiting. A magnetic resonance imaging (MRI) of the brain was performed at the ED, which revealed an SC mass in the right occipital scalp and a right cerebellopontine angle (CPA) mass. Excision of the SC mass revealed a well-circumscribed highly pigmented melanocytic tumor. The SC mass tumor cells were positive for melanocytic lineage markers. The histopathological features were between benign melanocytomas and malignant melanomas. The Ki67 and PHH3 IHCs confirm the intermediate grade of the tumors. An array-CGH (comparative genome hybridization) and next-generation sequencing analysis of the tumor DNA extracted from the formalin-fixed paraffin-embedded tissue reveals chromosome 6p gain and p.Q209P mutation in the GNAQ gene, respectively, consistent with the diagnosis of intermediate-grade melanocytoma.
authors: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors: Nitin
authors: N
authors: Marwaha
authors: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors: Jacqueline R
authors: JR
authors: Batanian
authors: Department of Neurosurgery, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors: Jeroen R
authors: JR
authors: Coppens
authors: Department of Neurosurgery, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors: Matthew J
authors: MJ
authors: Pierson
authors: Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors: Jennifer
authors: J
authors: Richards-Yutz
authors: Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors: Jessica
authors: J
authors: Ebrahimzadeh
authors: Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
authors: Arupa
authors: A
authors: Ganguly
authors: Department of Pathology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors: Miguel A
authors: MA
authors: Guzman
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D002530:Cerebellopontine Angle / Q000473:pathology; D002896:Chromosomes, Human, Pair 6 / Q000235:genetics; D055028:Comparative Genomic Hybridization; D003937:Diagnosis, Differential; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008067:Lipoma / Q000175:diagnosis*; D008297:Male; D008544:Melanocytes / Q000473:pathology*; D008545:Melanoma / Q000175:diagnosis* / Q000235:genetics; D008577:Meningeal Neoplasms / Q000175:diagnosis* / Q000235:genetics; D009154:Mutation; D012535:Scalp / Q000473:pathology; D040521:Subcutaneous Tissue / Q000473:pathology; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; C554061:GNAQ protein, human; D043802:GTP-Binding Protein alpha Subunits, Gq-G11
keywords: cancer; cutaneous neoplasm; melanocytic; melanocytic lesions; melanocytoma