Basaloid Squamous Cell Carcinoma of Gingiva: a New Case Report with Immunohistochemical Study

Abstract

Basaloid squamous cell carcinoma(BSCC)of the gingiva other than the tongue or floor of the mouth is uncommon. We reported a case of an 85-year-old man who was diagnosed with stage IV BSCC in the gingiva. An excision of partial resection mandible was performed and a functional elective neck dissection was carried out. The patientʼs recovery was uneventful until contralateral local regional lymph node metastasis was revealed by PET-CT. Histopathologically, the tumor consisted of cords and nests of basaloid cells with a cribriform growth pattern. Large nests frequently exhibited central comedonecrosis. The proliferated atypical basal cells were arranged in a gland-like space and extended to the mandible bone. Additional findings included hyaline material deposition in the stromal tissue, and keratin pearls or squamous cell components were observed. Immunohistochemically, CK17 showed great positive expression in all layers of the tumor cells. The basal cell marker of p63 revealed a high immunopositive rate with more than 90%. Strong positive expression of Ki-67 and p53 suggested high proliferative and malignant activities, and laminin5γ2 showed a moderate to strong positive expression. Our results indicated that BSCC was an aggressive tumor and CK17 might be a useful marker in differential diagnosis.