title: A Rare Case of Hydrocystoma of the Labial Commissure: Histopathology and Clinical Picture.
abstract: OBJECTIVE
  Hydrocystomas (HCs) are rare, benign, skin adnexal cystic tumors that may be either eccrine or apocrine.
  
  
  BACKGROUND
  Apocrine-HCs are cystic lesions that arise from the apocrine secretory coil, whereas eccrine-HCs are retention cysts of the eccrine duct. The commonest site is around the eyes, on the ears, scalp, chest, shoulders, or feet; HCs of the oral cavity are very rare.
  
  
  METHODS
  The case is reported of a 36-year-old man with a nodular lesion that was 7 × 5 mm in size on the labial commissure. The lesion was treated in direct contact with a diode laser that was 980 nm in continuous wave mode, with a 320 μm fiber at 1.8-2.0 W of power.
  
  
  RESULTS
  Complete healing occurred within 15 days. There were no adverse effects. The patient was carefully followed up, and there has been no recurrence. Histopathologically, the lesion was a multilocular cyst lined with a single-, and in some areas a double-layered epithelium with eosinophilic cytoplasm. Immunohistochemically, the secretory epithelium was positive for S-100 protein and negative for cytokeratin 5/6.
  
  
  CONCLUSIONS
  The histopathological and immunohistochemically diagnosis was of eccrine HC. The report stresses differential diagnosis versus cystic lesions of the labial commisure.
authors.affiliation: 1 Department of Surgical Medical Sciences and Integrated Diagnostic, University of Genoa , Genoa, Italy .
authors.forename: Francesca
authors.initials: F
authors.lastname: Angiero
authors.affiliation: 1 Department of Surgical Medical Sciences and Integrated Diagnostic, University of Genoa , Genoa, Italy .
authors.forename: Franco
authors.initials: F
authors.lastname: Ferrante
authors.affiliation: 1 Department of Surgical Medical Sciences and Integrated Diagnostic, University of Genoa , Genoa, Italy .
authors.forename: Rolando
authors.initials: R
authors.lastname: Crippa
authors.affiliation: 1 Department of Surgical Medical Sciences and Integrated Diagnostic, University of Genoa , Genoa, Italy .
authors.forename: Andrea
authors.initials: A
authors.lastname: Ottonello
authors.affiliation: 2 Department of Pathology, University of Milan Bicocca and San Gerardo Hospital , Monza, Italy .
authors.forename: Stefania
authors.initials: S
authors.lastname: Mauro
authors.affiliation: 2 Department of Pathology, University of Milan Bicocca and San Gerardo Hospital , Monza, Italy .
authors.forename: Maria Gabriella
authors.initials: MG
authors.lastname: Valente
mesh_terms: D000328:Adult; D001707:Biopsy, Needle; D005500:Follow-Up Studies; D018251:Hidrocystoma / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D007150:Immunohistochemistry; D053685:Laser Therapy / Q000379:methods*; D054023:Lasers, Semiconductor / Q000627:therapeutic use*; D008046:Lip / Q000473:pathology / Q000601:surgery; D008297:Male; D035583:Rare Diseases; D018570:Risk Assessment; D013544:Sweat Gland Neoplasms / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome
keywords: diode laser; hydrocystoma; labial commissure