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

Abstract

IntroductionInflammatory myopathies (such as dermatomyositis and polymyositis) are well-recognized paraneoplastic syndromes. However, paraneoplastic necrotizing myopathy is a more recently defined clinical entity, characterized by rapidly progressive, symmetrical, predominantly proximal muscle weakness with severe disability, and associated with a marked increase in serum muscle enzyme levels. Paraneoplastic necrotizing myopathy requires muscle biopsy for diagnosis, which typically shows massive necrosis of muscle fibers with limited or absent inflammatory infiltrates.Case presentationWe report the case of an 82-year-old Italian-born Caucasian man who was admitted to hospital because of heart failure and two drop attacks. Over the following days, he developed progressive severe weakness, dysphagia, and dysphonia. Testing showed increasing serum muscle enzyme levels. Electromyography showed irritative myopathy of the proximal muscles and sensorimotor polyneuropathy. Muscle biopsy (left vastus lateralis) showed massive necrosis of muscle fibers with negligible inflammatory infiltrates, complement membrane attack complex deposition on endomysial capillaries, and moderate upregulation of major histocompatibility complex-I. Computed tomography of the thorax showed a nodular mass in the apex of the right lung. The patient was diagnosed with paraneoplastic necrotizing myopathy. In spite of high-dose corticoid therapy, he died 1 month later because of his aggressive cancer. Subsequent electron microscopic examination of a muscle biopsy specimen showed thickened walls and typical pipestem changes of the endomysial capillaries, with swollen endothelial cells. Poorly differentiated adenocarcinoma of the lung was confirmed on post-mortem histological examination.ConclusionsParaneoplastic necrotizing myopathy is a rare syndrome with outcomes ranging from fast progression to complete recovery. Treatment with corticosteroids is often ineffective, and prognosis depends mainly on the characteristics of the underlying cancer. This case shows that paraneoplastic necrotizing myopathy may have an atypical appearance, and should be considered in elderly patients with neoplastic disease. In this case, the diagnosis was delayed by the unusual clinical picture that suggested heart disease rather than muscle disease.

Malignancy screening in autoimmune myositis among Australian rheumatologists

“…7,11 The evidence for NAM and sIBM is less in volume compared to DM and PM, and the epidemiological data are limited to small cohort studies and case series respectively. 12,13 In NAM a recent cohort study reported a cancer incidence rate of 11.5-21.4%. 14 3,15,16 The studies conclude that the rate of malignancy in DM and PM is significant when compared to that of the general population and detail relative risk (RR) ranges of 3.32-6.70 in DM and 1.19-2.25 in PM.…”

“…• 'A good history will lead to specific screening rather than submit every patient to a standard battery of tests in a shotgun approach' [28] • 'Increasingly I am now doing PET scans as usual screening has missed malignancy subsequently found on PET' [11] • 'Highly variable depending on History / Examination / Age / Ethnicity and disease features' [20] Theme: Triggers for initial screening • 'Especially NXP2' [55] • 'Only if response to treatment tapering is poor' [47] • 'When patients present with specific antibodies screening is not required.' [40] • '…Screening in inclusion body myositis is also favoured…' [35] Themes: Triggers for repeat screening • '…subtypes more commonly associated with malignancy eg Tif1… would guide me to be more proactive… if initial screening tests are negative' [52] • 'This is often risk driven / therapy driven and patient recovery status' [5] • 'The patient is often under regular review, any focal symptoms are followed up without delay' [30] • 'I will rescreen if there are warning bells' [12] • 'I would consider repeat screening if unexpected relapse' [11] Theme: Approach to repeat screening • '…little or no evidence to support present practice of repeated tests. Never helped me in 30+ years.…”

Paraneoplastic necrotizing myopathy in association with metastatic malignant melanoma: two case reports and a review of the literature

“…By comparison, CK is usually elevated 5 to 50 times the upper limit in polymyositis, and is increased up to 50-fold in dermatomyositis, though 10% of patients have normal CK regardless of severity [1] . Compared to non-paraneoplastic myopathy, paraneoplastic myopathy is more often associated with a dramatically elevated CK level [7] .…”

“…The classic clinical finding of necrotizing myopathy is symmetrical proximal muscle weakness without a rash [7,8] . Symptoms may mimic polymyositis, however, necrotizing myopathy progresses more rapidly and is more marked in severity in 30% of cases [9] .…”

“…Paraneoplastic necrotizing myopathy differs from primary myopathies in that prognosis is primarily dependent upon characteristics of the underlying malignancy [7] . Thus, treatment directed against the underlying malignancy is critical.…”