Paraneoplastic necrotizing myopathy and dermatomyositis in a patient with rectosigmoid carcinoma

Abstract

An 81-year-old woman with adenocarcinoma of the rectosigmoid presented with progressive muscle weakness and difficulty swallowing, with symptoms worsening following successful resection of the tumor. On examination, she had weakness primarily of lower limb proximal muscles, with no other abnormal findings. Laboratory tests showed significant elevation of creatine kinase, and EMG findings indicated myositis of the proximal muscles. While MRI showed increased signal intensity on T2-weighted images of the leg muscles, indicating inflammation, muscle biopsy found widespread necrosis with only weak and focal lymphocytic infiltration. A diagnosis of paraneoplastic necrotizing myopathy (PNM) was made, and immunomodulatory treatment initiated, with little response. Four months later she returned with exacerbation of symptoms, this time with skin changes pathognomonic of dermatomyositis (DM). A repeat MRI showed progression of inflammation, as well as necrotic foci. It is important to distinguish between paraneoplastic myopathies such as DM and PNM, with implications regarding treatment and prognosis.

Review: Immune‐mediated necrotizing myopathies – a heterogeneous group of diseases with specific myopathological features

“…The ultimate outcome is dependent on the evolution of the cancer, and successful treatment of the neoplasm will directly impact on the muscle symptoms ; however, the severity of necrotizing myopathy does not always parallel tumour progression . Difficulties in distinguishing paraneoplastic necrotizing myopathy from DM‐associated paraneoplasia are reflected by a recent report where both entities were diagnosed during the course of the disease .…”

“…distinguishing paraneoplastic necrotizing myopathy from DM-associated paraneoplasia are reflected by a recent report where both entities were diagnosed during the course of the disease [73].…”

Paraneoplastic necrotizing myopathy associated with adenocarcinoma of the lung – a rare entity with atypical onset: a case report

“…It is probable that our patient had a mild pre-existing sensory-motor axonal polyneuropathy, as mild fiber type grouping consistent with reinnervation was observed. The moderate upregulation of MHC-I with neoexpression on some non-necrotic fibers is a consistent feature of NAM, in contrast to the diffuse upregulation observed in polymyositis [9,11,14], and a cytokine response inhibiting upregulation of MHC-I in NAM has been hypothesized.…”

“…Paraneoplastic necrotizing myopathy is a rare condition associated with cancer and characterized by massive necrosis of muscle fibers in the absence of significant inflammation [1-11]. It is part of the distinct disease entity of necrotizing myopathy, which has been added as an independent new domain to idiopathic inflammatory myopathy [6,7].…”

Muscle weakness and myalgia as the initial presentation of serous ovarian carcinoma: a case report

“…Among them, paraneoplastic necrotizing myopathy (PNM) is a rare entity characterized by a rapidly progressive, symmetric, painful, predominantly proximal muscle weakness leading to severe disability [5]. PNM is mostly associated with primary cancers of the lung, breast, and gastrointestinal tract [6-8], and until now, it has not been reported in EOC. Notably, the myositides associated with EOC are usually dermatomyositis or polymyositis [9,10], not PNM.…”