Background: In Western countries, esophageal squamous cell carcinoma is usually advanced at presentation and is rarely diagnosed in situ. The authors studied an in situ squamous cell carcinoma that occupied the entire mucosa of a 9 cm length of esophagus, causing dysphagia for solid food in a woman aged 68 years.
Methods: The esophagectomy specimen contained a circumferential region of depressed tan mucosa in the middle and lower thirds, bordered above and below by normal squamous mucosa, without ulcer, stricture, or mass. The entire lesion was submitted for histology and evaluated with immunostains for cytokeratins and markers of Paget's cells, p53 mutation, and proliferation.
Results: The lesion involved 45 cm2 of mucosa. Large, atypical cells with frequent mitoses occupied the basal layers of the squamous epithelium and were often separated from more superficial maturing cells by acantholysis. Pagetoid spread of tumor cells into nonneoplastic surface and gland duct epithelium was prominent. The tumor cells expressed cytokeratins of low molecular weight, p53 gene product, and proliferating cell nuclear antigen (PCNA), but lacked markers usually seen in Paget's cells in the breast or vulva. No invasion was evident.
Conclusions: This extensive in situ squamous cell carcinoma of the esophagus resulted from pagetoid spread of tumor cells. These cells had a phenotype suggestive of origin from primitive epidermal stem cells and also had overexpressed p53 and PCNA, but they lacked the capacity to penetrate the basement membrane. Flat, erythematous areas of esophageal mucosa seen during endoscopy could represent early squamous cell carcinoma and should be biopsied.