Mycobacterium tuberculosis is the infectious agent responsible for tuberculosis (TB), one of the most common infectious causes of death in adults worldwide. It's protean manifestations may mimic different diseases in almost all clinical specialties. Herein we present a case of untreated tuberculosis sacroiliitis (SI) that evolved to disseminated pelvic disease mimicking ovarian carcinoma with peritoneal carcinomatosis. The patient complained of low back pain three years ago which was investigated with osseous scintigraphy and magnetic resonance imaging of the sacroiliac region and confirmed a left asymmetric SI. She was oriented to sporadically use of non-steroid anti-inflammatory drugs by the general physician who suspected spondiloarthropathy. Despite this, the symptoms got worse and progressed to abdominal pain, especially in hypogastric region, chronic diarrhea, severe night sweats, menstrual irregularity, weight loss, dyspareunia and undulant fever during the last year. She was admitted at this point and submitted to an exploratory video laparoscopic, the histopathology findings were strongly suggestive of disseminated pelvic TB showing granulomatous chronic inflammatory process with central caseous necrosis. The clinical team decided to initiate TB treatment, after 9 months of completed therapy, she was asymptomatic. The diagnosis of peritoneal tuberculosis usually is a challenge and invariably demands peritoneal biopsy. Mycobacterium tuberculosis can reach peritoneal tissue through the blood, lymphatic system and by contiguity. This case report presents an unusual form of pelvic and peritoneal disseminated tuberculosis preceded by a SI misdiagnosed as spondyloarthropathy.