Abdominal giant epidermoid cyst with squamous epithelial heterogeneous proliferation carcinoma in part of the cyst wall: a case report.

Background: Epidermoid cysts, which are rarely malignant, are common skin cysts. A giant epidermoid cyst is an epidermoid cyst with a diameter of >5 cm. Case Description: The purpose of this study was to describe the clinical presentation, surgery, and postoperative pathological tissue of a 69-year-old man who presented with a giant epidermoid cyst in the abdomen with heterogeneous hyperplasia of squamous epithelium in part of the cyst wall. The only symptom experienced by the patient was local tenderness. The mass was hard and fixed, and its boundary was clear. By performing ultrasound-guided puncture biopsy, the cytopathological results of the abdominal goitre puncture fluid showed that there were heterogeneous proliferating squamous epithelial cells on the right side. The immunohistochemical examination results of the puncture tissue biopsy on the right side showed a squamous cell carcinoma. On 2020-3-23, a tension-free repair of the right abdominal wall goitre was performed under general anaesthesia. The patient was discharged on the fifth postoperative day. The postoperative pathological examination indicated the following: (I) calcified highly differentiated squamous cell carcinoma was observed in part of the cystic wall; (II) the medial fibrous tissue of the striated muscle was covered with well-differentiated squamous epithelium; (III) part of the cyst wall was broken with histiocytosis and foreign body giant cell reaction, with visible scattered keratosis; and (IV) some areas of squamous epithelium were heterogeneously proliferating carcinoma, exhibiting well-differentiated invasive squamous cell carcinoma. Conclusions: As surgeons, it is crucial to remain vigilant and have a low threshold resection as well as thorough histological examination of specimens for early diagnosis and intervention, which can significantly improve patient outcomes.