Misdiagnosis of common variable immune deficiency.

We present details of a man who was originally diagnosed with sarcoidosis, based on a combination of nodal granulomatous inflammation and radiology confirming bilateral hilar lymphadenopathy with pulmonary infiltrates. The patient subsequently developed splenomegaly and idiopathic thrombocytopenic purpura (ITP) and, latterly, a severe cavitating pneumonia. Serum immunoglobulins were checked, confirming panhypogammaglobulinaemia, and his diagnosis was revised to common variable immune deficiency (CVID). CVID is a heterogeneous condition, which can mimic sarcoidosis with granulomatous organ involvement and is commonly complicated by autoimmune disorders, including ITP. Prompt recognition is important to allow early introduction of immunoglobulin replacement therapy to decrease infection frequency, reduce development of secondary disease complications and retard progression of tissue damage. Given the potential for misdiagnosis and delay in recognition of CVID, serum immunoglobulin measurement should be a first-line investigation in patients with suspected sarcoidosis, even if the presentation is 'typical'. Current international sarcoidosis guidelines should be revised accordingly.