Methods: Open lung biopsy performed Yale Thoracic Surgery and pathology performed by Yale Pathology.
Results: Our patient was a 51 year male with a chronic cough associated with recurrent fevers and lymphadenopathy. An immunological workup revealed polygammopathy with an IgA of 700, IgG of 4790, and IgE of 1204. He also had a very elevated CRP of 19.2. The broad differential for polygammopathy includes malignancies, chronic infections, and vasculitides. An elevated VEGF of 1200 indicated that the most likely diagnoses were MCD and IgG4 disease. A subsequent open lung biopsy showed plasmacytosis, which supported both diseases. However, an absence of definitive obliterative arteritis, along with the patient’s age and severe inflammatory state, led to the diagnosis of MCD.
Conclusions: MCD is a difficult diagnosis given the broad differential of polygammopathy. Clinical history and lab findings such as CRP, IgA level, and IL-6 may be used to point towards MCD. However, in our case study, a biopsy was needed to produce a definitive diagnosis as characteristic findings helped differentiate MCD from IgG4 disease.