A case of mononeuropathy multiplex with type II cryoglobulinemia, necrotizing vasculitis and low grade B cell...

To elucidate the cause and mechanisms of nerve fiber lesions in a case of mononeuropathy multiplex (MNM).

A 65-year-old man had a MNM for 6 months and no previous history of peripheral nerve impairment was known. He underwent a muscle and nerve biopsy by the same skin incision on the right leg.

Paraffin-embedded fragments from the superficial peroneal nerve and peroneous brevis muscle disclosed characteristic lesions of necrotizing vasculitis. Complement had low levels, but a search for cryoglobulinemia was negative. Two months later a purpura appeared in the lower limbs and a mixed Type II cryoglobulinemia was disclosed, whereas a search for hepatitis C virus (HCV) remained negative. Five months later the blood contained 8,600 lymphocytes/mm3 and a low grade B cell lymphoma was disclosed in the bone marrow.

Although not having HCV infection, our patient had mixed Type II cryoglobulinemia, necrotizing vasculitis and B cell lymphoma. Each of these three abnormalities might be in part responsible for nerve fibers impairment, with acute axonal degeneration. Mixed cryoglobulinemia must be searched carefully in patients with vasculitic neuropathy.