Lumps and bumps

Abstract

Over the course of 6 months, an 8-year-old boy presented with cutaneous lumps: a postauricular lump, a fluctuant scalp lump, a lump adjacent to his shin, and a firm chest wall lump. Although he was born in the UK, his family were from Kenya and had visited there after the symptoms started. After multiple courses of antibiotics and antifungals with no improvement, he underwent ultrasound scanning that showed erosion of bone under the lumps and computed tomographic (CT) scanning which showed tibial osteomyelitis. A biopsy of the chest wall lump showed granulomatous inflammation, and pus was extracted from the shin lump that was negative on Ziehl–Neilsen and Gram staining. A tuberculin skin test was equivocal, Quantiferon test positive and 12 days later Mycobacterium tuberculosis was cultured from the pus. The patient was started on quadruple antituberculous therapy and his skin lumps have improved. The long term outcome of the osteomyelitis remains to be seen.

BACKGROUND

Clinical conundrums are frequent and wide differentials are important in these situations. We present the case of a boy who had unusual symptoms, but lack of a response to common treatments did not alert the treating physicians to alternate diagnoses until he developed a potentially irreversible complication.

CASE PRESENTATION

A previously fit and well 8-year-old boy presented with a firm 2×2 cm tender lump behind his right ear (fig 1a). This was treated with two courses of antibiotics for 7 and 10 days by his general practitioner (GP) without improvement. One month later, he developed a 5×5 cm fluctuant lump on the vertex of his head, without any changes to his hair or scalp. He was treated with griseofulvin for 3 months by his GP for possible fungal infection, again without improvement. Four months after initial presentation, he received a bump on the left shin while playing football and within 2 days developed a lump at the site (fig 1c). The surface of the post-auricular lump broke down at this stage and oozed serous fluid, and his scalp lesion began to discharge pus. A further course of antibiotics resulted in no improvement. Five months after initial presentation, he developed a painless lump on his left chest wall (fig 1b) and he was referred to this hospital for further investigation.

Figure 1.

(a) Post-auricular lump 4 months after presentation; (b) chest wall lump; (c) left leg lump; (d) computed tomography scan of left leg; (e and f) pre- and post-treatment proximal tibial x rays.

Further history revealed that the family were originally from Africa (Somalia and Kenya) and had moved to England before he was born. The family had visited Kenya 1 month after the onset of symptoms but had not travelled abroad previously. He was fully vaccinated including BCG and had no pets. Everyone else in the family was well.

INVESTIGATIONS

Ultrasonography of the lumps revealed erosion of the bone adjacent to the scalp, shin and chest wall. He subsequently underwent ultrasound guided biopsy of the chest wall lesion that showed non-specific granulomatous inflammation. Pus obtained from the lesion on his leg was negative on Gram and Ziehl–Neilsen stains with no growth on bacterial culture after 48 h. A computed tomographic (CT) scan of his leg revealed inflammation and destruction of the proximal tibia with a fracture through the growth plate (fig 1d). On specific questioning his parents remembered that his uncle, who had lived with them the previous year, had “tuberculosis in his lymph nodes”. A tuberculin skin test (TST) was 17×15 mm, and a Quantiferon blood test was positive, so he was started on isoniazid, rifampicin, ethambutol, and pyrazinamide. After 12 days, the pus from his leg grew mycobacteria, which was shown on polymerase chain reaction (PCR) to be MTB complex. This was subsequently confirmed on culture to be fully sensitive Mycobacterium tuberculosis. His basic immune function was normal, including HIV testing. Further investigation of his interferon gamma/interleukin 12 pathway showed no abnormalities.

OUTCOME AND FOLLOW-UP

His lumps have decreased in size and his leg is improving on antituberculous therapy, although the long term impact of TB osteomyelitis on his limb growth is not yet known.

Comparison of pre- and post-treatment proximal tibial x rays (fig 1e,f) show complete resolution of osteomyelitis.

DISCUSSION

The oft-quoted title “TB or not TB?” highlights both the diagnostic dilemma TB poses but also the protean nature of tuberculous disease.^1–3 We report a case of a child presenting with multiple and disseminated skin lumps. Although cutaneous tuberculosis is well recognised, the lumps in our case were not consistent with the classical picture seen with cutaneous TB.⁴ Instead, the lesions behind the ear and on the chest wall started off as subcutaneous lumps consistent with post-auricular and intercostal lymph nodes, respectively. The fluctuant scalp lesion was more unusual and more likely to be cutaneous TB due to the location of this lesion. The soft tissue swelling on his shin was consistent with underlying bone inflammation secondary to TB osteomyelitis.

The TST was barely positive, even for a child who has had BCG (current UK guidelines suggest TST is positive with induration >15 mm with previous BCG). Furthermore, the biopsy showed non-specific granulomatous inflammation, with no evidence of caseation. In this situation the interferon-gamma release assay (IGRA) was positive and suggested tuberculosis. The IGRA tests measure interferon production in response to antigens specific to M tuberculosis, which distinguish infection from most other mycobacteria, including M bovis used in BCG. However, there is cross-reactivity with a few atypical mycobacterial species, namely M kansasii, M marinum and M szulgai. Despite this, in general IGRA testing is increasingly becoming a useful adjunct to the diagnosis of tuberculosis, particularly its ability to differentiate TB from atypical mycobacterial infection and the effect of BCG on TST.⁵

The important lesson from this case, albeit one with an unusual presentation, is that failure to respond to antibiotics and antifungal medication should lead the clinician to think early about alternate diagnoses. Unusual presentations of TB should be considered in these situations, especially in children from backgrounds with high rates of the disease. Early diagnosis is more likely to prevent complications, particularly in sites of disease that may cause long term and irreparable damage.

We can find no other cases where a child has presented like this with multiple skin lumps of different origin, although TB lymphadenopathy alone is relatively common.

LEARNING POINTS

• Failure of antibiotics and antifungal medication should lead the clinician to think early about alternate diagnoses.

• Unusual presentations of tuberculosis should be considered, especially in children from backgrounds with high rates of the disease.

• Early diagnosis of TB is more likely to prevent complications such as osteomyelitis.