Primary Peritoneal Sarcoidosis Causing an Omental Cake

Omental cake is an ominous sign and is mainly caused by malignancy.1 Omental cake refers to infiltration of the omental fat by material of soft tissue density. In computed tomography (CT) scans, omental cake is diagnosed by demonstrating an abnormally thickened greater omentum. There are many causes of omental cake, of which intraperitoneal tumor spread is the most frequent. Other less common causes of this finding include inflammatory conditions such as tuberculosis, Crohn’s disease, phlegmonous pancreatitis, and granulomatous enterocolitis. In the current article, we describe a case of an omental cake in a young patient, its rare cause, and its histopathological appearance. The current case is of a 43-year-old woman who was admitted to the emergency department with abdominal pain that started 1 day before admittance. The patient denied any urinary symptoms, vomiting, diarrhea, constipation, or fever. On physical examination, her blood pressure was 150/87 mmHg, heart rate 80 beats/min, and temperature 36.7°C. Abdominal examination was unremarkable apart from slight tenderness in the right lower quadrant with no organomegaly. Laboratory values were unremarkable. On gynecological examination, several myomas and bilateral ovarian cysts were found. This examination was summarized as one with no evidence of an acute gynecological problem. An abdominal CT scan demonstrated an enlarged uterus, ovarian cysts, a small hypodense lesion in the liver, and suspected peritoneal spread with omental cake formation involving the anterior abdomen and colon (Fig. 1). No obvious primary lesion was seen. Following these results the patient was referred for a further workup, which included upper endoscopy and colonoscopy, both of which were normal; tumor markers were normal except CA-125, which was 60; and a mammogram, which was normal. As a result of the fact that no primary lesion was found, a decision was made to perform a diagnostic laparoscopy. In the laparoscopy, numerous white patchy dots were found on the peritoneal surface of the inner abdominal wall, the liver, and the small intestine (Fig. 1). No primary lesion could be identified. A biopsy was taken from the greater omentum. The patient had an uneventful recovery from the surgery. Microscopic examination of the biopsy specimen showed fragments of omentum and lymph nodes showing noncaseating granulomas with focal fibrosis. ZN, PAS, Giemsa, and methenamine silver stains were all negative. The specimen was CD 68-positive (Fig. 2). All these results were consistent with the diagnosis of primary peritoneal sarcoidosis. The patient was then started on steroid therapy and is in a close follow-up with our rheumatologic specialists. An omental cake is an ominous sign and is mainly caused by malignancy.1 The differential diagnosis for these lesions of peritoneal spread where no primary lesion can be found includes malignant mesothelioma, cystic mesothelioma, ovarian carcinoma, primary peritoneal carcinoma, desmoplastic small round cell tumor, histiocytoma, gastrointestinal stromal tumors, and lymphoproliferative malignancies as well as some forms of sarcoma. The differential diagnosis also includes benign tumors derived from lymphatic, vascular, neuromuscular, or fatty tissues. To our surprise, the source of the omental cake in the current case was sarcoidosis. Sarcoidosis is characterized by inflammation of tissues resulting in the formation of the small aggregations of cells, or granulomas. The onset of the disease may be gradual or sudden. In some individuals, the disease comes and goes spontaneously throughout life, and in others, it may totally disappear, although this process can take years. Like in our case, some patients with sarcoidosis are asymptomatic and diagnosis is only incidental.2 Sarcoidosis most commonly affects the lungs, but may also affect the skin, eyes, lymph nodes, muscles, Address correspondence and reprint requests to Zvi H. Perry, M.D., M.A., Surgical Ward A, Soroka University Medical Center, P.O. Box 151, Beer-Sheva 64101, Israel. E-mail: zperry@bgu.ac. il.