Poorly Differentiated Squamous Cell Carcinoma in an Atomic Bomb Survivor.

Abstract

Dear Editor: Many epidemiological studies of atomic bomb survivors in Japan demonstrate that exposure to radiation increases the risk of cancers, especially leukemia, in most organs1. The risk of non-melanoma skin carcinoma in atomic bomb survivors is elevated2, and the most common primary skin tumors among 152 skin tumors among patients exposed to atomic bomb radiation were basal cell carcinoma (42%), followed by squamous cell carcinoma (SCC) (26%), Bowen's disease (13%), and malignant melanoma (6%)3. Here, we report a case of poorly differentiated SCC in an atomic bomb survivor. An 86-year-old Japanese woman visited our hospital with a one-month history of subcutaneous tumor in the inguinal region. She noticed a tumor on her the left side of waist when she was 46 years old. She was exposed to atomic bomb radiation in Hiroshima at the age of 19 years. Physical examination revealed a 32×40-mm reddish dome-shaped tumor on her the left side of the waist (Fig. 1A) and a 65×72-mm painful subcutaneous tumor on her left inguinal region (Fig. 1B). Blood examination revealed no abnormal changes. Whole-body computed tomography revealed no remarkable changes. Fluorodeoxyglucose-positron emission tomography revealed abnormal uptake in the tumor of on the waist and left inguinal lymph nodes. Histopathological examination of the waist tumor demonstrated numerous tumor cells throughout the dermis and subcutis (Fig. 1C). Atypical large tumor cells had irregular nuclear contours and prominent nucleoli (Fig. 1D). Immunohistochemistry showed the tumor cells were positive for keratin, CK7, p63, p40, and NSE but negative for CK20, chromogranin A, synaptophysin, thyroid transcription factor-1 (TTF-1), CD56, Melan-A, S-100, and EBER (Fig. 2A~E). The results of the histological and immunohistochemical examinations of the inguinal tumor were same. On the basis of these findings, she was diagnosed with poorly differentiated SCC in the waist and metastasis in the inguinal lymph nodes. Tumors in the waist and inguinal regions were resected, and she was subsequently treated with electron beam radiation (total dose: 59 Gy). Eight months later, a metastatic lesion in the left lung was observed, but she refused additional treatment. Fig. 1 (A) Reddish dome-shaped tumor on the left side of the waist. (B) Painful subcutaneous tumor on the left inguinal region. (C, D) Histopathological examination of the waist tumor (HE C: ×40, D: ×1,000). (C) Numerous tumor cells ... Fig. 2 Immunohistochemical examination of the waist tumor. Tumor cells stained positive for (A) keratin and (B) CK7, and negative for (C) chromogranin A, (D) CK20, and (E) thyroid transcription factor-1 (A~E: ×400). Tumor cells were positive for keratin as well as squamous cell markers p63 and p40. The common markers of neuroendocrine carcinomas, including Merkel cell carcinoma, CK20, chromogranin A and synaptophysin, were negative. TTF-1, a marker of primary thyroid and lung carcinoma, was negative. These immunohistochemical results and the low differentiation pattern of tumors on hematoxylin & eosin staining lead to a final diagnosis of poorly differentiated SCC. Regarding the relationship between the extent of tumor differentiation and atomic bomb radiation exposure, the frequency of poorly differentiated adenocarcinoma of stomach in atomic bomb survivors is significantly higher than that in non-exposed individuals4. Nevertheless, the association between atomic bomb radiation exposure and poorly differentiated SCC in our patient is speculative. A recent study reports multiple basal cell carcinomas were developed in atomic bomb survivors more than 40 years after radiation exposure5. Thus, exposure to atomic bomb radiation might influence the risk of cancers; therefore, dermatologists should perform long-term surveillance for skin carcinomas in atomic bomb survivors.