title: Managing a Rare Malignant Sweat Gland Tumor Invading the Brain: Case Report and Literature Review.
abstract: Malignant sweat gland adnexal tumors are rare with an incidence of 0.001%. Of these, clear cell hidradenocarcinoma is an extremely uncommon subtype that accounts for 6% of malignant eccrine sweat gland tumors. They occur commonly in the head, neck, and extremities. Although they have a propensity for local recurrence, intracranial extension with brain invasion is extremely rare.
  
  
  
  We report a 76-year-old man with a large, recurring, ulcerated, fungating scalp swelling of 14 years who presented with focal seizures and drowsiness. Neuroimaging revealed a massive tumor arising from the scalp to invade the left parietal lobe and extending to the right side with occlusion of the superior sagittal sinus. The overlying parietal bone was lytic with a "moth-eaten" appearance. He underwent wide excision of the scalp lesion, near-total cerebral tumor decompression followed by titanium mesh cranioplasty, rotation flap reconstruction of the scalp, and adjuvant radiotherapy to the skull vault. Histopathology revealed clear cell hidradenocarcinoma. Whole-body positron emission tomography scan did not reveal any other lesion. At 24 months' follow-up, he remains recurrence free.
  
  
  
  We report a rare indolent case of clear cell hidradenocarcinoma invading the brain, which was managed with near-total decompression and adjuvant radiotherapy. Intracranial extension in such aggressive tumors poses challenges in management, and regular neuroimaging surveillance is advised.
authors.affiliation: M S Ramaiah Institute of Neurosciences, M S Ramaiah Medical College, Karnataka, India. Electronic address: anirudhbmc@yahoo.co.in.
authors.forename: Aniruddha Tekkatte
authors.initials: AT
authors.lastname: Jagannatha
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS) Bengaluru, Karnataka, India.
authors.forename: Mansoor A
authors.initials: MA
authors.lastname: Khan
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS) Bengaluru, Karnataka, India.
authors.forename: Shrithi
authors.initials: S
authors.lastname: Karanth
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS) Bengaluru, Karnataka, India.
authors.forename: Umesh
authors.initials: U
authors.lastname: Srikantha
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS) Bengaluru, Karnataka, India.
authors.forename: Ravi
authors.initials: R
authors.lastname: Varma
authors.affiliation: Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS) Bengaluru, Karnataka, India.
authors.forename: Anita
authors.initials: A
authors.lastname: Mahadevan
mesh_terms: D018250:Acrospiroma / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*; D000368:Aged; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D011859:Radiography; D012535:Scalp; D013544:Sweat Gland Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery*
keywords: Clear cell hidradenocarcinoma; Cranioplasty; Sweat gland adnexal tumor; Wide excision