BASAL CELL ADENOMA
- Definition : It is a benign epithelial neoplasm composed of basaloid cells which are uniform and monomorphous.
- They are categorized into solid, trabecular, tubular and membranous type.
- Site – Parotid, submandibular glands, upper lip (intra oral location) in decreasing order of frequency
- Age – peak incidence – 7th decade of life. Incidence increases as the age increases.
- Clinical features – presents as solitary well defined nodules except membranous type which is multifocal.
- Gross – sharply circumscribed with or without capsule. cut section is homogenous grey white. some tumors may be cystic .
- Microscopy –
- Tumor is composed of monomorphic population of basaloid cells which are small, uniform cells with pale eosinophilic to amphophilic cytoplasm, with distinct cell borders and round to oval nuclei.
- Two types of cells are present : cells having scant cytoplasm and more basophilic nuclei and larger cells having pale basophilic nuclei containing one or more small basophilic nucleoli.
- Larger cells predominate and smaller cells are clustered at the periphery. nuclei at the stromal interface appear as aligned in palisade.
- Solid type : Tumor cells are arranged in large sheets, small nodules or irregularly shaped, some times anastomosing broad bands in collagenous stroma.
- Trabecular type – composed of narrow anastomosing cords of uniform basaloid cells supported by a loosely collagenous almost myxoid stroma. Cells are small dark and show palisading of the epithelial nuclei along the stromal interface.
- Tubular type – Duct cell differentiation and lumen formation is more prominent in the tubular type
- Membranous type – Islands of tumor cells separated by thick bands of hyaline material which is the basal lamina by tumor cells. Tumor cells are arranged as “Jigsaw puzzle”. Tumor has multinodular pattern of growth.
- Differential diagnosis
- Basal cell adenocarcinoma – Atypical features.
- Adenoid cystic carcinoma – Atypical features and perineural invasion
- Cellular pleomorphic adenoma – Fibromucoid stroma distinguishes.
- Canalicular adenoma – Cell morphology and site distinguishes
- Treatment and prognosis – Surgical excision. Recurrence occurs with membranous type due to multinodular growth.
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Basal cell adenoma : Basaloid tumor cells arranged in interconnecting costs, nests, and tubular pattern which are separated by hyalinized stroma (H&E, ×100).
Basal cell adenoma : Basaloid cells arranged in nests and tubular pattern separated by hyaline material. peripheral nuclei show palisading (H&E,X400)
Basal cell adenoma : Basaloid cells arranged in nests and tubular pattern separated by hyaline material. peripheral nuclei show palisading (H&E,X400)
Basal cell adenoma: Basaloid cells arranged in nests and tubular pattern separated by hyaline material. peripheral nuclei show palisading (H&E,X400)