Pancreatic Adenocarcinoma Presented as Paraneoplastic Dermatomyositis Complicated With Rhabdomyolysis: Case Report and Review

Introduction

Dermatomyositis is an infrequent autoimmune inflammatory myopathy characterized primarily by symmetric proximal muscle weakness and pathognomonic cutaneous signs, including Gottron’s papules and heliotrope rash [1,2]. Systemic involvement includes lung disease, with interstitial lung disease representing an important cause of mortality and morbidity. It is estimated that 35% to 40% of patients diagnosed with dermatomyositis or polymyositis will have interstitial lung disease during the course of myositis. Due to the involvement of the esophageal-pharyngeal muscle, patients with dermatomyositis frequently present with dysphagia, which is a risk factor for underlying malignancy. Other manifestations include nasal speech and aspiration pneumonia [3].

Approximately 15% to 30% of adult patients with dermatomyositis have an underlying malignancy, with the ovaries, lungs, stomach, breasts, and pancreas being the most prevalent sites. The prevailing theory suggests that immune-mediated cross-reactivity between neoplastic cells and muscle or skin antigens drives this association [4,5]. However, atypical initial presentations—particularly those dominated by acute kidney injury and massive muscle necrosis—can significantly obscure the diagnosis and delay the detection of the primary tumor [6].

While dermatomyositis is a recognized paraneoplastic phenomenon, its emergence as severe rhabdomyolysis precedes a cancer diagnosis, while in the clinical milieu of pancreatic adenocarcinoma, this phenomenon maintains an extraordinary scarcity in the literature [7,8].

Our report details a unique case in which rhabdomyolysis and dermatomyositis served as the presenting features of pancreatic cancer. Our objective is to underscore the necessity of identifying such unusual clinical patterns early and to advocate for rigorous malignancy screening in all cases of adult-onset inflammatory myopathy.

Case Report

Methodology

STUDY DESIGN:

This study was a retrospective, descriptive case report with a narrative literature review. The objective was to describe a rare case of dermatomyositis with rhabdomyolysis as a paraneoplastic effect of pancreatic adenocarcinoma. We also compared its course and outcomes with those in previous cases.

CASE IDENTIFICATION AND DATA COLLECTION:

This case of dermatomyositis with rhabdomyolysis was identified during routine clinical care at a tertiary hospital. Clinical, laboratory, radiology, and histopathology data were collected from hospital electronic records and the patient’s chart.

Data collected included demographics: age, sex, smoking status, family and medical history; clinical features: onset and progression of fatigue, rash, muscle pain, weakness, dysphagia, and respiratory symptoms; laboratory parameters: CK, liver enzymes (AST, ALT), renal profile (urea, creatinine), electrolytes, and autoimmune serology, such as ANA and extractable nuclear antigen; radiological findings: chest X-ray, CT scan of the abdomen and pelvis; histopathology: biopsy of the pancreatic mass confirmed adenocarcinoma; therapeutic interventions: corticosteroid treatment, hemodialysis, antibiotics, and symptomatic care; and clinical outcome: response to treatment, functional improvement, and follow-up findings.

ETHICAL CONSIDERATIONS:

This study adhered to the principles of the Declaration of Helsinki. All patient identifiers were removed for confidentiality. The case was reviewed and approved by the hospital ethics committee before submission (IRP approval number: 11757).

LITERATURE REVIEW METHOD:

A comprehensive literature review was performed to put this case in context. Searches were conducted in PubMed, Google Scholar, and Scopus from inception to May 2025. Keywords and Boolean operators included “dermatomyositis” AND “rhabdomyolysis” AND “pancreatic cancer” OR “paraneoplastic myopathy” OR “paraneoplastic dermatomyositis”.

The inclusion criteria were as follows: English-language case reports, series, or reviews discussing dermatomyositis, polymyositis, or rhabdomyolysis associated with pancreatic malignancy, and studies providing clinical details, treatment approaches, and outcomes. The references of retrieved papers were manually checked for additional studies. Data were extracted on demographics, symptoms, cancer type, diagnostic findings, management, and outcomes.

DATA AND STATISTICAL ANALYSIS:

In this single-patient study, descriptive qualitative analysis was used. We summarized laboratory test results and clinical features to demonstrate disease progression. No inferential statistics were done due to the data type. For the literature review, data from comparable case reports were placed in tables and qualitatively reviewed to find clinical patterns, treatment responses, and outcomes. This improved understanding through comparison.

Several publications met the inclusion criteria, including case reports, reviews,and articles discussing paraneoplastic dermatomyositis and rhabdomyolysis associated with pancreatic malignancy, as summarized in Table 2.

Discussion

The present case illustrates the intricate relationship between autoimmune myopathies and underlying malignancies, especially the paraneoplastic form of dermatomyositis related to pancreatic adenocarcinoma. Even though the standard indicators of dermatomyositis include cutaneous rashes and proximal muscle weakness, the initial presentation here (dominated by acute kidney injury and fulminant rhabdomyolysis) obscured the underlying paraneoplastic etiology. Such diagnostic challenges are well-documented; literature suggests that paraneoplastic symptoms can precede a cancer diagnosis by several months, often mimicking other conditions such as toxic rhabdomyolysis or steroid-induced myopathy [9,10].

Recent studies increasingly link pancreatic neoplasms and dermatomyositis. It is hypothesized that tumor-associated antigens, including TIF1-γ and NXP-2, trigger immune cross-reactivity that targets regenerating muscle fibers [11]. Furthermore, recent molecular studies have identified autoantibodies directed against DNA mismatch repair proteins, specifically hMSH2 and hPMS1. These proteins are expressed both in pancreatic adenocarcinoma tissues and the inflammatory environment of myopathies, suggesting a shared autoimmune mechanism. This molecular overlap indicates that the immune response initially directed at the tumor may inadvertently drive the systemic inflammatory damage observed in muscle tissues [12].

Regarding clinical management, this case reinforces the vital need for immediate malignancy screening in adults newly diagnosed with dermatomyositis, particularly when they exhibit acute systemic decline or dysphagia [13]. Statistical data from a meta-analysis of 20 separate studies indicates that the likelihood of cancer is most significant during the first 12 months after diagnosis [14]. Therefore, screening with CT imaging for the chest, abdomen, and pelvis can help identify hidden malignancies [3]. Additional cancer screening options should be guided by the patient’s clinical features and ethnic background and may include mammography, gynecologic evaluation, ultrasonography, and tumor marker assessment. Alternatively, fluorodeoxyglucose positron emission tomography/CT is a valuable option, providing comparable diagnostic yield [15].

In our experience, the patient’s rapid response to corticosteroid treatment, followed by a targeted oncological assessment, supports the theory that combining immunosuppression with cancer therapy leads to superior clinical results [7,16]. However, the rare combination of renal failure and rhabdomyolysis remains a diagnostic puzzle. Finally, because malignancy can reappear or even appear for the first time up to 3 years later, ongoing observation remains indispensable [17].

Our case is comparable to most of the cases mentioned in the review (Table 2), as our patient presented with profound muscle breakdown and markedly elevated CK levels, with variable response to steroid therapy. It could suggest that markedly elevated CK levels reflect an exaggerated paraneoplastic immune response.

One of the limitations of this case is that our patient’s general clinical condition was poor; therefore, a muscle biopsy was not performed, and myositis-specific anti-TIF1-γ and anti-NXP-2 antibodies were not available at our institution.

Conclusions

This case emphasizes that unexplained rhabdomyolysis should raise suspicion of malignancy-related inflammatory myositis. It has also been demonstrated that prompt steroid administration, a multispecialty evaluation, and early clinical suspicion can significantly improve the patient’s prognosis.