Case 10 -

Superficial Basaloid Squamous Carcinoma, Endoscopic Mucosal Resection Professor Kaiyo Takubo Department of Human Tissue Research, Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan Miwako ARIMA, MD Department Gastroenterology Saitama Cancer Center Hospital Saitama-ken , Japan

Clinical history: A 66-year-old man with recurrent invasive squamous cell carcinoma of the mid-pharynx was hospitalized for radical surgery. He had previously received radiation therapy for mid-pharyngeal carcinoma. He had drunk an equivalent of 36 mg of ethanol per day for 45 years, and his Smoking Index was 920. Before the radical operation, he underwent endoscopic examination of the esophagus and stomach for cancer screening, and was found to have a slightly elevated lesion in the esophagus. A biopsy specimen from the lesion was diagnosed as a carcinoma. After radical surgery for the mid-pharyngeal carcinoma, endoscopic mucosal resection (EMR) was performed twice for the esophageal carcinoma. The patient has been well with no evidence of recurrence of the pharyngeal or esophageal carcinoma for 3 years after the last EMR. The histologic slides used for this presentation were prepared from the last EMR specimen. Case 10 - Slide 1 Click to view with ImageScope Click to view with a Web-Based Viewer Pathologic Diagnosis: Basaloid squamous carcinoma of the esophagus associated with squamous cell carcinoma in situ Pathologic findings: Depth of invasion, sm1 (carcinoma invading within 200 μm in the tunica submucosa in the EMR specimen). Lymphatic invasion negative, venous invasion negative. Resection margin is negative for carcinoma. Incidence of Basaloid Squamous Carcinoma of the Esophagus Basaloid squamous carcinoma was observed as a minor component in 7.3% of usual squamous cell carcinomas in our Japanese series. In a review of 502 cases of esophageal malignancy in Korea , Cho et al. (2000) found 18 cases of basaloid squamous carcinoma, an incidence of 3.6%. At the time of biopsy, the incidence of basaloid squamous carcinoma is very low, suggesting that this type of carcinoma tends not to be diagnosed correctly by biopsy. Morphological Features of Basaloid Squamous Carcinoma of the Esophagus Macroscopically, if superficial, basaloid squamous carcinomas often have a plateau-type or predominantly subepithelial-type appearance. When advanced, they tend to have a complex ulcerated appearance. Basaloid squamous carcinomas are characterized histologically by large cancer nests in which basaloid malignant epithelial cells are arranged in solid or trabecular patterns. Unlike basal cell carcinoma of the skin, a palisading pattern of tumor cells along basement membranes is relatively rare. The tumor cell nests may be centrally necrotic. Small keratinizing foci may be found on occasion, and a clear trabecular arrangement of cancer cells may sometimes be seen. Basaloid squamous carcinomas with a trabecular pattern may in fact resemble carcinoid tumors, and basaloid squamous carcinomas have actually been confused with primary carcinoid tumors of the esophagus in some case reports. It is common for hyaline basement membrane material, which stains PAS-positive, to be distributed within and around the tumor cell nests. With immunohistochemical stains this material is positive for laminin and type IV collagen. Staining for epithelial mucin is negative. Unlike adenoid cystic carcinoma, basaloid squamous carcinoma does not show a two-cell-type pattern of myoepithelial and ductal epithelial cells, but the distinction between these entities remains unclear. Venous invasion is often seen in advanced cases; this invasion may occur into relatively large vessels, indicating that this entity has a propensity for vascular invasion. In cytologic preparations the tumor cells are usually cohesive and resemble the basal cells of squamous epithelium. In general they have scanty cytoplasm, which stains light green with the Papanicolaou method; some naked nuclei may also be seen. The nuclei are round or oval and irregular in size. Basement membrane material may also be seen in cytologic smears. Basaloid squamous carcinomas are somewhat similar to small cell carcinomas cytologically, but can be distinguished from them by the lack of file arrangements with nuclear molding and by the presence of thickened nuclear membranes. Electron microscopy shows that the hyaline material consists of prominent multilayered basement membranes surrounding the tumor cells. Prognosis of Basaloid Squamous Carcinoma It is considered that the prognosis of this entity in the esophagus is poorer than that of usual squamous cell carcinoma, and is similar to that of basaloid squamous carcinoma of the oral cavity and upper respiratory tract. A study that reviewed 17 cases of basaloid squamous carcinoma of the esophagus documented only one patient who had survived for more than 5 years. Other reports, however, have stated that the prognosis of this tumor, if detected at an early stage, is similar to that of usual esophageal squamous cell carcinoma (Shimizu et al.). Yoshioka et al. (2004) reviewed 60 cases of basaloid squamous carcinoma of the esophagus; the outcome of cases at stages I, IIa, and IIb (UICC) was similar to that of usual squamous cell carcinoma, but cases at stages III and IV had a poorer outcome than usual squamous cell carcinoma (Figure 16). References Cho K-J, et al. Basaloid squamous carcinoma of the oesophagus: a distinct neoplasm with multipotential differentiation. Histopathology 36:331-340, 2000. Shimizu H, et al. A case of basaloid carcinoma of the esophagus. Jpn J Gastroenterol Surg 25:102-106, 1992. Takubo K, et al. Basaloid-squamous carcinoma of the esophagus with marked deposition of basement membrane substance. Acta Pathol Jpn 41:59-64, 1991. Takubo K, et al. Morphological heterogeneity of esophageal carcinoma. Acta Pathol Jpn 39:180-189, 1989. Yoshioka S, et al. Progressive analysis of four cases of basaloid cell carcinoma of the esophagus and reported cases in Japan. Jpn J Gastroenterol Surg 37:290-295, 2004.