Table of Contents
Definition / general | Clinical features | Case reports | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Differential diagnosisCite this page: Handra-Luca A. Keratocystoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/salivaryglandskeratocystoma.html. Accessed March 28th, 2024.
Definition / general
- Rare benign tumor with multicystic spaces lined by squamous cells with focal solid epithelial nests
- First reported by Seifert (as choristoma, Virchows Arch 1999;434:355) and Nagao (Mod Pathol 2002;15:1005)
Clinical features
- Very rare neoplasm of children / adults, < 20 cases reported
- Usually parotid gland; may derive from salivary ducts undergoing squamous metaplasia
- Excision appears to be adequate treatment
Case reports
- 37 year old man with parotid nodule (J Clin Pathol 2010;63:758)
Microscopic (histologic) description
- Benign tumor with multicystic spaces, without lobular architecture, lined by squamous cells with focal solid epithelial nests
- Parakeratotic and orthokeratotic keratinization without a granular layer
- Outer layer has bud-like protrusions
- Cells have abundant eosinophilic cytoplasm and bland, uniform nuclei
- May have collageneous stroma, expansive growth
- Focal foreign body reaction against keratin
- Occasional normal mitotic figures
- No necrosis, no invasion, no angiolymphatic invasion, no perineurial invasion, no atypia, no mucous cells
Positive stains
- Cytokeratin (AE1 / AE3, CK14, CK17; focal CK13, focal CK19), Ki67 (outer basal layer only), collagen type IV positive material around cysts / cell nests
Negative stains
Differential diagnosis
- Epidermal / dermoid cysts
- Mucoepidermoid carcinoma
- Necrotizing sialmetaplasia
- Squamous cell carcinoma
- Squamous metaplasia in other conditions