Esophageal carcinoma cuniculatum: report of 9 cases.

Carcinoma cuniculatum, a unique variant of well-differentiated squamous cell carcinoma, has been only rarely reported in the esophagus. We report 9 cases of esophageal carcinoma cuniculatum diagnosed on esophagectomy specimens in 7 men and 2 women during a 20-year period. All but 1 of the patients presented with persistent or progressive dysphagia. All patients had an esophageal mass or lesion on endoscopic examination. In 8 cases (88.8%), the tumor was located in the distal esophagus. Burrowing was noted on the tumor surface in 2 recent cases on macroscopic examination. All carcinomas were invasive either at the mucosa (n=2), submucosa (n=1), muscularis propria (n=4), adventitia (n=3), or adventitia and lung (n=1). All carcinomas demonstrated a common histologic pattern characterized by hyperkeratosis, acanthosis, dyskeratosis, abnormal keratinization, keratin-filled cyst/furrows, koilocyte-like cells, intraepithelial neutrophils, and focal cytologic atypia. In situ hybridization for human papillomavirus subtypes was negative in all 10 tumors tested. None of the cases showed lymph node metastasis. Two patients died postoperatively due to complications. The remaining patients were followed up for a median duration of 84 months (48 to 214 mo). During the follow-up period, 3 patients died 49, 66, and 214 months after esophagectomy at the ages of 66, 68, and 91 years, respectively; death in these 3 cases was not related to recurrence/metastases of esophageal cancer. Four patients were alive without disease at 48, 49, 84, and 87 months after curative resection. Our report identifies a common histomorphologic pattern of esophageal carcinoma cuniculatum and supports the fact that surgical resection of the tumor by esophagectomy provides long-term survival even in patients with T3 tumor.