A diagnostic dilemma: differentiating between granulomatosis with polyangiitis and tuberculosis

Abstract

Granulomatosis with polyangiitis (GPA, formerly Wegener's granulomatosis) can present diagnostic difficulties for the clinician as there can be considerable overlap in features with tuberculosis (TB). Indeed, there are documented cases both of coexisting TB and GPA, and cases wrongly diagnosed as GPA when in fact TB was the underlying diagnosis. This lesson presents a case of GPA where TB was also considered as a differential and highlights the diagnostic and management difficulties when this is the case.

Fig 1.

Chest X-ray showing numerous bilateral ill-defined nodular opacities.

Fig 2.

Histology slide showing multi-nucleate giant cells taken from patient's nasal biopsy.

Fig 3.

HRCT slice in which ill-defined opacities and possible early cavitation can be seen. HRCT = high resolution computed tomography.

Fig 4.

CRP of the patient during the course of admission. Five plasma exchanges were given over 5 consecutive days the patient stayed in ITU. The patient was transferred to ITU on day 17, and plasma exchange was started. CRP = C-reactive protein. ITU = intensive care unit.