Rinsho Shinkeigaku (Clinical Neurology)

Case Report

A case of post-surgical inflammatory neuropathy with lower-extremity weakness after surgery for anorectal malignant melanoma that showed the effectiveness of immunotherapy

Rei Asano, M.D.1), Yuki Kitazaki, M.D.1), Masamichi Ikawa, M.D., Ph.D.1), Hidetaka Kurebayasi, M.D., Ph.D.2), Haruki Koike, M.D., Ph.D.3) and Tadanori Hamano, M.D., Ph.D.1)

1) Department of Neurology, University of Fukui Hospital
2) Department of Gastrointestinal, University of Fukui Hospital
3) Department of Neurology, Nagoya University Graduate School of Medicine

A 59-year-old man with past histories of bronchial asthma and chronic sinusitis underwent transanal resection of anorectal malignant melanoma with general anesthesia. On the third day after surgery, he presented with subacute weakness with right dominant hypoesthesia in the bilateral lower limbs. Tendon reflexes were diminished without pathological reflexes. Blood examination showed increased eosinophils (2,058/µl) and elevated serum immunoglobulin E (675.0 IU/ml). Cerebrospinal fluid examination showed elevated protein (200 mg/dl) without pleocytosis (<5/µl). A nerve conduction study suggested multiple mononeuropathy with motor and axonal dominance in the right tibial, peroneal, and sural nerves. Because of eosinophilia and his past medical history (i.e., bronchial asthma and chronic sinusitis), we initially suspected eosinophilic polyangiitis granulomatosis (EGPA) as the cause of postoperative polyneuropathy. However, his neurological symptoms did not improve despite the decreased eosinophil count after tumor resection, which was inconsistent with EGPA. We biopsied the left sural nerve to exclude EGPA and make a diagnosis. Pathological findings revealed no demyelination, axonal degeneration, or eosinophil infiltration with granuloma formation; however, lymphocyte-dominated inflammation was observed around the epineurial small vessels. Thus, the patient was diagnosed with early onset post-surgical inflammatory neuropathy (PIN) based on his clinical course and the pathological findings. On post-surgery day 48, oral administration of prednisolone (40 mg/day) was started. His neurological symptoms improved quickly and remarkably. Our case suggests that, when multiple mononeuropathy develops early after surgery, PIN should be considered as a differential diagnosis to initiate appropriate treatment based on the pathological condition of neuropathy.
Full Text of this Article in Japanese PDF (5555K)

(CLINICA NEUROL, 60: 762－767, 2020)
key words: post-surgical inflammatory neuropathy, peripheral neuropathy, malignant melanoma, nerve biopsy, immunotherapy

(Received: 7-Mar-20)