Primary clear cell peritoneal carcinoma

The long delay between asbestos exposure and the development of mesothelioma will likely result in an increased incidence of mesothelioma in our industrialized societies. Radiation therapy is another factor known to induce these tumors. We describe a rare case of foamy looking mesothelioma in a 63-year-old patient with a long oncology history of a supposed peritoneal carcinomatosis. The pathologist was faced with a diagnostic pitfall as this peritoneal clear cell tumor expressed transcription factor binding to immunoglobulin heavy constant mu enhancer 3 (TFE3) at the nuclear level. Fortunately, the pathologist performed an extensive panel of immunomarkers, leading to a final diagnosis of epithelioid mesothelioma. Thus, we describe the first case of mesothelioma expressing TFE3. Note that there was no rearrangement of TFE3 in fluorescence in situ hybridization.

A 52-year-old woman with abdominal pain and a feeling of incomplete evacuation visited a local clinic. Enlargement of the right ovary was detected, and the patient was referred to the gynecological department of our hospital. CT and MRI revealed a round-shaped mass, 8 cm in diameter, with cystic and solid components in the Douglas pouch. The patient underwent a laparotomy under the diagnosis of ovarian cancer. Intraoperatively, both the ovaries appeared normal and the tumor strongly adhered to the rectum and uterus. An exploratory laparotomy was performed; the tumor was identified as unresectable, and the patient was referred to our department after the surgery. PET-CT revealed nodules in the liver and peritoneum, in addition to the main tumor. Gastrointestinal endoscopy and immunohistochemical examination of a needle biopsy of the main tumor did not lead to the identification of the primary lesion. Thus, debulking surgery was performed to alleviate the patient's complaints. Histologically, the tumor was diagnosed as a primary peritoneal clear cell carcinoma. One month after surgery, multiple liver metastases and swelling of the peritoneal lymph nodes occurred. Six courses of dose-dense TC therapy were administered, and the patient achieved a complete response. At 8 months after surgery, the patient is still alive without tumor recurrence.

Peritoneum is a site for both primary and secondary tumors. Primary peritoneal tumors are fairly rare. The most common primary tumors of the peritoneum are malignant mesothelioma and serous papillary adenocarcinoma. Clear cell carcinoma of the peritoneum is extremely rare and often misdiagnosed as mesothelioma, serous carcinoma, or metastatic adenocarcinoma, so it represents a diagnostic challenge for both clinicians and pathologists. Up to date, to the best of our knowledge, only 11 cases of primary peritoneal clear cell carcinoma have been reported in the English literature. Distinguishing this tumor of the peritoneum versus ovarian carcinoma can be problematic. Herein, we report a rare case of primary peritoneal clear cell carcinoma occurring in a 49-year-old woman, along with a review of the literature.