A 62-year-old man presents with progressive hoarseness. Laryngoscopy reveals a friable exophytic mass on the true vocal cord. Biopsy shows dysplastic squamous epithelium with full-thickness loss of normal polarity, numerous mitoses including atypical forms, but the basement membrane is intact. What is the most accurate diagnosis?
- A Squamous cell carcinoma in situ ✓
- B Invasive squamous cell carcinoma
- C Severe dysplasia (CIN III equivalent)
- D Squamous papilloma with moderate dysplasia
Correct answer: A. Squamous cell carcinoma in situ
Explanation
Full-thickness loss of normal epithelial polarity and maturation with atypical mitoses, in the absence of basement membrane invasion, defines carcinoma in situ (CIS). The intact basement membrane is the key feature that distinguishes CIS from invasive carcinoma. The term severe dysplasia/CIN III is used specifically for cervical epithelium; in the larynx the equivalent lesion is designated squamous CIS.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.