PERITONEAL KERATIN GRANULOMAS MIMICKING PERITONEAL CARCINOMATOSIS: A POTENTIAL DIAGNOSTIC PITFALL

Abstract Introduction/Objective Keratin granulomas from a primary uterine cancer can present as peritoneal tumor nodules, mimicking peritoneal carcinomatosis. Endometrial adenocarcinomas with viable peritoneal tumor implants and/or involvement of bladder or bowel mucosa are categorized as stage IV disease. We present a rare case of endometrial adenocarcinoma of the uterus with squamous differentiation and multiple peritoneal nodules of keratin granulomas, masquerading as peritoneal carcinomatosis. Methods/Case Report A 68-year-old female with insignificant past medical history presented with complaints of postmenopausal bleeding for the past four months. Physical examination was unremarkable. Transvaginal ultrasound showed a 4.9 cm echogenic mass in the uterus. The endometrial biopsy showed squamous debris with atypical cells suspicious of malignancy. Endometrial curettings revealed endometrial adenocarcinoma, endometrioid type with squamous differentiation, FIGO Grade 1. Subsequently, she underwent hysterectomy with bilateral salpingo- oophorectomy. Intraoperatively, multiple suspicious nodules on the sigmoid colon and in the pelvis were identified, of which excisional biopsies and pelvic peritoneal washing were taken. Microscopic examination of the resection confirmed endometrial adenocarcinoma, FIGO Grade 1, nuclear grade 1, with extensive foreign body giant cell reaction to dead squamous cells (ghost cells). Cytologic examination of the peritoneal washing was unremarkable and excisions of the sigmoid serosal and peritoneal nodules showed pink eosinophilic laminated nodules surrounded by inflammatory cells including plasma cells, lymphocytes and multinucleated giant cells without any viable tumor cells. Results (if a Case Study enter NA) NA Conclusion Keratin granulomas are a foreign body reaction to keratin deposition from the squamous component of endometrioid adenocarcinoma. The pathogenesis of this foreign body response to keratin is considered to be a trans- tubal spread of keratin through retrograde shedding from the fallopian tubes. In the absence of viable tumor cells, it appears to have no negative prognostic significance. Careful microscopic examination of peritoneal keratin granulomas is imperative to avoid erroneous upstaging of the tumor and the subsequent advanced treatment.