Necrotizing autoimmune myopathy associated with POEMS syndrome report

Case Report: Monoclonal Gammopathies of Clinical Significance-Associated Myopathy: A Case-Based Review

Monoclonal gammopathies of clinical significance (MGCS)-associated myopathy is a group of muscular MGCS-based rare manifestations. It mainly includes amyloid light chain (AL) amyloidosis and sporadic late-onset nemaline myopathy with monoclonal gammopathy of undetermined significance. When myopathy manifests as the initial or sole clinical symptom, it can often be delayed or misdiagnosed as other myopathies. We report the case of a 60-year-old man who initially presented with fatigue and muscle weakness of the symmetric proximal lower limbs. Muscle biopsy did not reveal mononuclear cell infiltration, atrophy, necrosis, or positive Congo red staining results. The results of serum protein electrophoresis and immunofixation electrophoresis were negative. No specific diagnosis was established. After 1 year, the patient was diagnosed with AL amyloidosis after myocardial and fat pad biopsies were performed and myopathy was diagnosed as AL amyloidosis-associated myopathy after reassessment. The patient received CyBorD regime chemotherapy and achieved hematological and organ remission. Therefore, we reviewed the clinical and pathological manifestations of MGCS-associated myopathies. Based on published articles and the present case, we conclude that comprehensive screening for MGCS in unexplained myopathy is essential to avoid misdiagnosis or delayed diagnosis.

POEMS syndrome: a unique presentation and a diagnostic challenge

We present the case of a previously well, 70-year-old lady who presented with gait deterioration and a clinicoradiological picture of myositis with T2-enhancement on MRI of the distal lower limb muscles. A muscle biopsy pointed towards neurogenic amyotrophy and a mixed demyelinating and axonal sensorimotor polyneuropathy was confirmed on nerve conduction studies. This was initially thought to be secondary to a myeloproliferative disorder but a positron emission tomography scan showed uptake in the left hip which corresponded to what was previously reported as a subchondral cyst on CT. A biopsy showed this to be a plasmacytoma in the context of a normal serum protein electrophoresis and a polyclonal increase in light chains on serum-free light chain estimation. The patient was started on treatment 6 months after the presentation for a diagnosis of POEMS syndrome, by which time, the patient had become bed-bound and fully dependent.