Adenoid squamous cell carcinoma of the oral cavity.

Because immunohistochemical features of adenoid squamous cell carcinoma (AdSCC) of the oral cavity is unclear, the author reports herein AdSCC in the gingival with an emphasis on immunohistochemical features. A 73-year-old woman presented with a left lower gingival tumor. The tumor was mildly elevated tumor measuring 1.5 x 1.5 x 0.5 cm. Dentist's diagnosis was granulation tissue, and a biopsy was taken. The biopsy showed proliferation of carcinoma cells arranged in cords, and squamous and tubular differentiations were noted in places. The biopsy diagnosis was adenosquamous carcinoma. Tumor excision with resection of mandibular bone was performed. The resected tissue showed a mixture and squamous cell carcinoma and tubular formation. Gradual merges between the two and acantholytic features of the squamous cell carcinoma element were seen. Both components were free from mucins. Both components were positive for pancytokeratins (AE1/3, CAM5.2) +++, cytokeratin (CK) 5/6 +, CK34βE12 ++, CK7 +, CK14 +++, CEA +, CA19-9 +, CA125 +, p53 +++, p63 +++, KIT + and MUC1 ++. Both components were negative for CK8, CK18, CK19, CK20, EMA, vimentin, TTF-1, desmin, myoglobin, S100 protein, melanosome, smooth muscle actin, CD34, CDX2, CD10, chromogranin, synaptophysin, NSE, CD56, lysozyme, CD68, MDM2, PDGFRA, MUC2, MUC5AC, and MUC6. Since both components were positive for squmaous cell carcinoma markers (CD5/6, CK34βE12, and p63) and adenocarcinoma markers (CEA, CA19-9, CA125, MUC1), this case of AdSCC appears an intermediate form between adenocarcinoma and squamous cell carcinoma. The margins were negative. No metastasis was found by imaging techniques. The patient is now free from tumor and is followed up carefully.