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A 7-year-old South Asian boy was evaluated in a district general child assessment unit following a 4-week history of daily fevers with associated pain and swelling in the thumb and middle finger phalanges of the right hand. There was no history of cough, weight loss, night sweats or trauma. On examination, he appeared well with no anaemia or jaundice. There was a spindle-shaped deformity of the right thumb and middle finger, with concomitant non-tender right axillary lymphadenopathy. No other joints were affected. The rest of the physical examination was unremarkable.
Radiographs of the affected fingers demonstrated fusiform soft tissue swelling (Figure 1A) with smooth periosteal reaction (Figure 1B). Subsequent CT of the thorax demonstrated necrotic axillary (Figure 2A) and hilar lymphadenopathy (Figure 2B) with ‘tree-in-bud’ change in the superior segment of the left lower lobe (Figure 1C).
A Mantoux test (protein purified derivative) was positive with an induration of 30 mm. QuantiFERON (interferon-γ release assay) was also positive. Haemoglobinopathy screen was negative. A biopsy of the affected phalanges revealed granulomatous inflammation with the presence of necrosis and giant cells; Mycobacterium tuberculosis PCR was positive. The diagnosis of tuberculous dactylitis and pulmonary tuberculosis were made given the constellation of clinical, radiological and laboratory findings: he was commenced on an appropriate antituberculosis drug regimen.
Dactylitis, diffuse fusiform swelling of a digit(s), has a wide differential diagnosis including:1
infectious (osteomyelitis, syphilitic and tuberculous (spina ventosa));
haematological (sickle cell disease and leukaemia);
arthropathic (psoriatic, hyperparathyroidism, gout and sarcoidosis).
Contributors AF: involved in the clinical care of the patient; obtained informed consent; co-wrote the manuscript text. GT: involved in the clinical care of the patient; reviewed the manuscript text. MP: extracted, reformatted and labelled all the imaging; wrote all the figure legends; co-wrote the manuscript text.
Competing interests None declared.
Patient consent Obtained from guardian.
Provenance and peer review Not commissioned; externally peer reviewed.
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