Indian Journal of Dermatology
: 2021  |  Volume : 66  |  Issue : 4  |  Page : 447-

Immune-Mediated Necrotizing Myositis Presenting with Cutaneous Lesions

Bruno de Castro e Souza1, Isaura A Fasciani2, Bethania C C Swiczar2, Rodrigo de H Mendonça3, Neusa Y S Valente2,  
1 Department of Dermatology, Univesity of São Paulo, Divisions of Dermatology, São Paulo, SP, Brazil
2 Divisions of Dermatology, Hospital of the State Public Servant of São Paulo, São Paulo, SP, Brazil
3 Divisions of Neurology, Hospital of the State Public Servant of São Paulo, São Paulo, SP, Brazil

Correspondence Address:
Bruno de Castro e Souza
Department of Dermatology, Univesity of São Paulo, Divisions of Dermatology, São Paulo, SP

How to cite this article:
e Souza Bd, Fasciani IA, C Swiczar BC, Mendonça RH, S Valente NY. Immune-Mediated Necrotizing Myositis Presenting with Cutaneous Lesions.Indian J Dermatol 2021;66:447-447

How to cite this URL:
e Souza Bd, Fasciani IA, C Swiczar BC, Mendonça RH, S Valente NY. Immune-Mediated Necrotizing Myositis Presenting with Cutaneous Lesions. Indian J Dermatol [serial online] 2021 [cited 2023 Feb 2 ];66:447-447
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Full Text

The idiopathic inflammatory myopathies are a group of unusual disorders characterized by motor weakness secondary to a muscular inflammatory process. These myopathies are classified into five subgroups: dermatomyositis, polymyositis, sporadic inclusion body myositis, antisynthetase syndrome, and immune-mediated necrotizing myositis (IMNM).[1],[2] In IMNM, extra muscular involvement is uncommon.[3] Herein, we describe a case report of IMNM with cutaneous involvement.

An eight-year-old girl presented with a four-month history of erythematous and infiltrated plaques with ill-defined borders on the extensor surface of the superior and inferior extremities. [Figure 1]. The patient reported muscle weakness to perform physical activities. Gottron papules, heliotrope rash, or signs of cutaneous calcinosis were not seen, and the neurological examination indicated proximal muscular weakness. Laboratory examination showed glutamic-oxaloacetic transaminase = 383 U/L (RV = 13-39), glutamic pyruvic transaminases = 626 U/L (RV = 0–35), protein kinase C = 10,186 U/L (RV = 0–145), and normal values for blood cells. Antinuclear antibody (ANA), antibodies to the signal recognition particle (anti-SRP), and antibodies against HMG-CoA reductase (anti-HMGCR) were negative. Hence, we hypothesized dermatomyositis. A skin biopsy revealed an epidermis with discrete hyperkeratosis and spongiosis, and superficial and deep perivascular inflammatory infiltrates containing lymphocytes, histiocytes, and numerous neutrophils within the walls of the blood vessels, but with no fibrinoid necrosis on the vessel walls [Figure 2]. The periodic acid Schiff (PAS) staining showed no enhancement within the epidermal basement membrane, while the Alcian Blue staining was negative for mucin. Direct immunofluorescence was negative.{Figure 1}{Figure 2}

Nuclear magnetic resonance spectroscopy showed diffuse signal alteration, characterized by a T2 hyper signal within the hip and thigh muscles, intravenous paramagnetic contrast enhancement, and absence of ventral muscular atrophy, consistent with myositis. A muscle biopsy showed a myopathic pattern with numerous necrotic muscle fibers, degenerating and regenerating fibers without any apparent inflammatory process, and increased expression of the major histocompatibility complex I (MHC I) molecules [Figure 3]. These findings made the diagnosis of autoimmune necrotizing myopathy.{Figure 3}

The patient underwent three sessions of pulsed therapy with 800 mg of methylprednisolone. Next, methotrexate 15 mg once weekly and prednisone 60 mg/day were introduced with complete response.

Depending on the antibodies' positivity, the condition is classified as IMNM anti-SRP, IMNM anti-HMGCR, or IMNM autoantibody negative. This latter category represents almost one-third of all cases and can be a marker of hidden neoplasia, but it would be unlikely in a young person.[2],[4] Suzuki et al. (2015), in a case series of 100 patients with IMNM anti-SRP, related only six cases of cutaneous rash. However, they neither described the cutaneous lesions nor obtained skin biopsies from these patients.[5]

The negativity of autoantibodies and skin biopsy is essential to exclude the possibility of dermatomyositis since the histological findings of this case differ from that expected for this condition. Also, the histopathological muscle examination was crucial to differentiate between IMNM and dermatomyositis. In the first, histopathology shows necrotizing myopathy with subtle or no inflammation, findings consistent with our patient.[1],[2],[3] In the latter, perifascicular atrophy and microangiopathy support the diagnosis.

To our knowledge, this is the first report of histopathology of a cutaneous lesion of the IMNM. It is essential that the dermatologist knows this condition and expands the differential diagnosis of myositis with possible dermatological manifestations.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

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Conflicts of interest

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2Aussy A, Boyer O, Cordel N. Dermatomyositis and immune- mediated necrotizing myopathies: A window on autoimmunity and cancer. Front Immunol 2017;8:992.
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