The diagnostic clues of extra pulmonary tuberculosis include: chronic lymph adenopathy, pleural effusion and thickening, chronic monoarthritis and spondylodiscitis being a child, and having an immunosuppressive disease (HIV+) (
5, 6, 9). Diagnosis is routinely difficult and elusive ( 4). Lymph nodes, pleura, pericardium, central neural system, urinary and musculoskeletal system and skin are the most common sites of extra pulmonary tuberculosis ( 1, 2, 4, 6).
Skin and soft tissue involvement is a rare form of Mycobacterium tuberculosis infections (1% - 2%) (
5, 7). However, detection of Mycobacterium tuberculosis is always an important part of differential diagnosis of skin and soft tissue involvement in endemic areas ( 9). Cutaneous tuberculosis arises from cutaneous mycobacterium inoculation, contiguous transmission from bone, joint and synovial infection and in very rare cases by the hematogenous route, and overall it seems that cutaneous tuberculosis without bone involvement is uncommon ( 5- 7, 9).
Cold abscess is an uncommon form of cutaneous tuberculosis that can be single or multiple and with or without fistula. These abscesses are usually multi-lobulated and occur in immunocompromised patients (
1, 5). In addition, cold abscesses do not involve toxic symptoms and cause minimum inflammation ( 10).
Mycobacterium tuberculosis can easily involve surrounded soft tissue of infected bone or joint and produce cold abscess, yet some of these abscesses have been reported without any bone or joint involvement (
Sometimes tuberculosis abscesses are mistaken with tumors (
11). Tuberculosis should be considered in differential diagnosis of cold abscesses, especially in immunosuppressive patients ( 5).
The diagnostic methods of tuberculosis cold abscesses include:
1. Laboratory methods: smear, culture and PCR of drained material (
2. Imaging methods: sonography, Computerize Tomography (CT) scan and MRI (method of choice) (
2, 4, 5, 8).
Aspiration of the abscess and laboratory examination is usually adequate for diagnosis confirmation (
9). These abscesses are not distinguishable from pyogenic abscesses in imaging methods ( 1).
In MRI, the abscess was indicated by a hypo signal in T1 and hyper signal in T2 and not enhanced with gadolinium while the abscess wall was enhanced.
Most tuberculosis abscesses in the literature were treated with medical and surgical procedures (
8). At present, the preferred treatment for these abscesses is CT guided drainage ( 6). Indications of surgical procedures in these patients include:
1. Treatment failure with drainage
2. The conditions that suggest drainage is contraindicated
3. Surgical procedure required for other reasons (
Response to treatment is based on the improvement of clinical manifestations, resolving of the abscess on imaging studies and decrease of ESR (
Treatment regimens for pulmonary and extra pulmonary tuberculosis do not differ (
This report presented a rheumatoid arthritis patient with a forearm tuberculosis cold abscess. Immunosuppression in the context of corticosteroid use was an important risk factor for this patient. Drainage (without CT guidance) associated with standard anti-tuberculosis regimen was very effective for this patient.
In conclusion, it is necessary for clinicians to consider tuberculosis in immunosuppressive patients with abscesses.