CASE 2901 Published on 06.09.2005

Peritoneal tuberculosis following infliximab therapy

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

Mir N, Kennedy C, Jones A

Patient

47 years, male

Categories
No Area of Interest ; Imaging Technique CT, CT, CT
Clinical History
A 47-year-old male patient, with longstanding inflammatory arthritis, recently started on infliximab treatment presented with anorexia, ascites and fever.
Imaging Findings
A 47-year-old male patient presented with anorexia, abdominal pain and bloating, weight loss and fever. He had a long history of a severe, inflammatory arthritis, which had caused a major damage to a number of his joints requiring multiple joint replacements. Six months prior to this presentation, he had been assessed and started on anti-tumour necrosis factor alpha treatment and had received a total of three doses at monthly intervals. One month after the last infusion, he had been admitted to the hospital with general malaise, anorexia, abdominal pain, ascites and fever. His blood cultures had grown Staphylococcus aureus, and a CT scan of his abdomen had shown low attenuation lesions in the spleen which were felt to represent septic emboli, as well as a large amount of ascites (Fig. 1). Analysis of the ascitic fluid revealed a moderate number of lymphocytes. No organisms, acid-fast bacilli or malignant cells were seen. Other investigation results including a chest X-ray photographs, echocardiogram and bone scan were found to be normal. For three weeks, he was adminstered antibiotics intravenously and was put on oral antibiotics for a further 4 weeks.The diagnosis made on his discharge was "septic episode after infliximab with probable splenic abscesses". Two weeks after he had completed oral antibiotics adminstration, he re-presented with the above symptoms. Investigations revealed a C-reactive protein level of 200 mg/dl and his erythrocyte sedimentation rate was 129 mm. A full blood count, urea and electrolytes, liver function tests, blood cultures, urine sample and CXR were all found to be normal. A repeat CT scan of the abdomen (Figs. 2 and 3) done again showed a low attenuation lesions in the spleen, but also generalized soft tissue infiltration of the omentum, highly suggestive of omental caking. The rest of the solid organs, small and large bowels, appeared normal. There was no retroperitoneal lymphadenopathy. Due to the reported increased incidence of malignancy in patients on anti-TNF alpha treatment, the patient was referred to the general surgeons for an investigation of an underlying malignancy. An ultrasound guided omental biopsy was performed by the radiologist. A microscopy that was done showed the presence of multiple caseating granulomas, which was strongly suspected for tuberculosis. The culture of the omental sample was found to be positive at five weeks. The patient was referred to the infectious diseases unit and started on anti-tuberculous chemotherapy. The patient had been vaccinated with BCG as a child and had no previous TB contacts. As is the routine prior to starting infliximab, our patient was screened for TB with a normal CXR and a 2+ reaction to the tuberculin skin test.
Discussion
Tuberculous peritonitis is known to be usually due to a haematogenous spread from pulmonary TB. Patients present with progressive ascites, accompanied later by fever, anorexia and weight loss. Oedema, hepatosplenomegaly and generalized lymphadenopathy may appear later in the clinical course of the disease. Ascitic fluid typically contains numerous lymphocytes, and Mycobacterium tuberculosis organisms are only identified in 5% of cases. The culture is positive in 80% of cases. The diagnosis can be made by doing a biopsy and the culture of the peritoneal tissue is usually obtained at laparoscopy or laparotomy. Patients receiving anti-TNF alpha therapy are thought to be at an increased risk of malignancy and opportunistic infections. Smith et al. (1) have reported the rapid onset of cutaneous squamous cell carcinoma in patients with rheumatoid arthritis after starting anti-TNF alpha therapy. Lori Brown et al. (2) identified 26 cases of lymphoproliferative disorders (majority non-Hodgkins lymphoma) a short interval after starting treatment with anti-TNF alpha. Cases of tuberculosis following such treatment have also been reported (3). The Food and Drug Administration (FDA) analyzed reports of TB after infliximab treatment that had been received via the Adverse Event Reporting System (4). They found a total of 70 cases of TB in 147,000 patients. The median time for development of TB was 12 weeks after starting the treatment. Of the patients, 48 had developed TB after three infusions or less and forty had extra-pulmonary disease, including four patients with peritoneal TB. The authors concluded that active tuberculosis may develop soon after starting infliximab treatment and that patients should be screened for latent infection. In this case, the finding of Staphylococcus aureus in blood cultures misled the clinicians as to the underlying cause of the patient's initial presentation with anorexia and ascites. The identification of omental caking on ultrasound allowed a percutaneous biopsy to be carried out thereby preventing the need for adminstering a general anaesthetic. This case highlights two important points. The first, that TB should be considered as a diagnosis in all patients who are immuno-compromised and present with a fever, and secondly, to remember that TB is known as "the great mimicker".
Differential Diagnosis List
Peritoneal tuberculosis after infliximab therapy.
Final Diagnosis
Peritoneal tuberculosis after infliximab therapy.
Case information
URL: https://www.eurorad.org/case/2901
DOI: 10.1594/EURORAD/CASE.2901
ISSN: 1563-4086