Peritoneal tuberculosis mimicking advanced ovarian carcinoma: an important differential diagnosis to consider

BACKGROUND: Female patients who present with ascites, adnexal masses and elevated CA125 levels are typically presumed to have advanced ovarian carcinoma. This can lead to radical surgery with its associated morbidity. An important differential diagnosis to consider is tuberculous peritonitis which can present in a similar manner and responds well to medical treatment. CASE PRESENTATION: A 44 year old female presented with abdominal distension, weight loss and low grade fever. Her CA125 level was 909 U/ml. Imaging studies revealed an adnexal lesion and ascites. The lungs appeared normal and a Mantoux test was negative. Ovarian malignancy was highly suspected. Cytology of ascites was negative for malignant cells. The patient subsequently developed a large pleural effusion which was drained and negative for malignant cells and acid fast bacilli. Repeat imaging revealed a ‘tree in bud’ appearance of the lung parenchyma and dense ascites. Histology from diagnostic laparotomy revealed caseating granulomas with epithelioid cells and Langhan’s type giant cells. The patient responded well to antituberculosis therapy with normalization of CA125 levels, confirming the diagnosis of peritoneal tuberculosis. CONCLUSION: CA125 levels lack specificity, with elevated levels encountered in many benign and malignant conditions, including tuberculosis. There are a few discriminating features that suggest a diagnosis of tuberculous peritonitis rather than ovarian carcinoma. Apart from chest findings which may not always be present, smooth peritoneal thickening and a dirty omentum on CT favours a diagnosis of peritoneal tuberculosis compared with nodular thickening of the peritoneum and omentum in peritoneal carcinomatosis. PCR and ADA testing of ascitic fluid can also be helpful. When these tests are negative or unavailable then diagnostic laparoscopy or laparotomy should be performed with the aid of frozen section to avoid unnecessary radical surgery in cases of peritoneal tuberculosis.