Three cases of atypical mycobacterial cervical adenitis

Atypical mycobacterial cervical adenitis (AMCA) in children is a condition that still presents management dilemmas.

CASE HISTORIES

Case 1

A girl of 5 developed a persistent discharging sinus in the left submandibular region after an incomplete excision biopsy at another centre (Figure 1). At further operation the sinus and matted lymph nodes adherent to the internal jugular vein were removed with preservation of the lower cranial nerves. She was also treated with clarithromycin for three weeks preoperatively and three weeks postoperatively. Mycobacterium avium was cultured after eight weeks. The wound healed well, with good cosmetic outcome.

Figure 1.

Neck ulcer with a central discharging sinus after initial incomplete excision

Case 2

An 8-year-old boy was referred with persistent left-sided cervical lymphadenopathy. He was otherwise well. There was no response to treatment with co-amoxiclav. AMCA was suspected and, after three weeks' treatment with clarithromycin and ciprofloxacin (which was continued for three weeks postoperatively), he underwent complete excision of affected glands. The final outcome was again good. Tissue cultures were negative after twelve weeks of incubation but special stains showing acid-fast bacilli, together with granulomatous inflammation on histological sections, lent strong support to the clinical diagnosis.

Case 3

A girl of 3 had a persistent cystic violaceous lump at the angle of the right mandible (Figure 2). After needle aspiration of the lump a persistent parotid salivary fistula developed. Slides prepared with special stains yielded acid-fast bacilli. There was no response to six weeks' dual therapy with clarithromycin and ciprofloxacin. Total parotidectomy, with the attendant risk of facial nerve injury, was a serious consideration at this stage. M. malmoense, sensitive to rifampicin, was then cultured from the aspirated material. Surgery was postponed and treatment with rifampicin was started. The fistula healed and the lump involuted after three months' treatment with this single agent (Figure 3). She remains under review.

Figure 2.

Persistent lump at angle of the mandible, with violaceous hue

Figure 3.

Fibrosis and skin scarring after healing of parotid salivary fistula

COMMENT

The incidence of infections due to M. tuberculosis and atypical mycobacteria has increased in the past decade. This increase is in part related to the AIDS epidemic, but the rate of mycobacterial infections in immunocompetent individuals seems to be increasing independently¹. This is borne out by figures published by the Scottish Mycobacteria Reference Laboratory, with 93 isolates recorded in 1990 and 172 in 2000.

In children the most common site of clinically significant atypical mycobacterial infection is the superficial lymph nodes of the head and neck. A group of lymph nodes is usually involved, most often located in the anterior superior cervical chain or submandibular area. The great majority of children with AMCA are not immunologically impaired. The three children reported here were completely free of constitutional symptoms and remained afebrile with normal white cell counts.

The epidemiological evidence suggests that these infections are acquired from environmental sources, including soil, water, dust, and aerosols². The predilection for younger children is probably related to their tendency to put objects contaminated with soil, dust or standing water in their mouths. The tendency to present in the winter months may reflect the greater likelihood of viral upper respiratory infection in this season, which might allow the causal organism easier access via inflamed mucous membranes³.

The differential diagnosis of AMCA is extensive, but important conditions to exclude are tuberculous adenitis, infectious mononucleosis, cat-scratch disease, brucellosis, actinomycosis, nocardiosis, toxoplasmosis, malignancies (especially lymphoma), and cystic hygroma. The greatest difficulty usually is in distinguishing between adenitis caused by atypical mycobacteria and adenitis due to M. tuberculosis. Lack of contact with an adult with tuberculosis, a small or absent reaction to a tuberculin skin test, and a poor response to standard antituberculous chemotherapy favour the diagnosis of AMCA. Non-specific laboratory investigations such as blood counts, erythrocyte sedimentation rate, and serum biochemistry tend to be normal in children with AMCA and are of no diagnostic value. Definitive diagnosis depends upon isolation of the organism in culture. Cultures for atypical mycobacteria may, however, be negative even when infection is present. Only about 50% of excised diseased lymph nodes will be culture positive⁴. With a mean time of about eight weeks for culture and twelve weeks for sensitivity results⁵, initial diagnosis depends greatly on the clinical features.

Many forms of therapy for AMCA have been practised, including surgical excision, antituberculous chemotherapy and a combination of surgery and chemotherapy. In case 1, incomplete excision was complicated by chronic sinus formation and discharge. Needle aspiration and incision and drainage likewise tend to be complicated by sinus or fistula formation, as demonstrated by case 3. A sinus can persist for months or years⁶, with serious cosmetic implications. In case 3, treated with rifampicin, healing was marked by fibrosis and scarring of the skin; excision of residual scar tissue may eventually be necessary for cosmetic reasons.

The role of chemotherapy in the treatment of AMCA is not entirely clear. Whilst atypical mycobacteria are generally resistant to first-line antituberculous agents there have been many well-documented cases of AMCA resolving during treatment with such medications⁷. More recent experience favours surgical excision over prolonged antituberculous therapy. For recurrent AMCA after surgery, treatment with newer chemotherapeutic agents such as the macrolides (e.g. clarithromycin) and fluoro-quinolones (e.g. ciprofloxacin) has yielded encouraging results⁸, but no controlled trials have yet been reported. The treatment of choice is complete surgical excision, with or without chemotherapy. It is both diagnostic and therapeutic.