Paraneoplastic dermatomyositis with atypical features associated with a solid pseudopapillary pancreatic neoplasm

Abstract Dermatomyositis (DM) is an autoimmune inflammatory myopathy that may occur as a paraneoplastic syndrome, most commonly associated with ovarian, lung, and gastrointestinal malignancies. Solid pseudopapillary pancreatic tumor is a rare neoplasm with low malignant potential, and to our knowledge only one case has previously been reported in association with DM. We present the case of a 21-year-old woman with six months of proximal muscle weakness, dysphagia, and cutaneous lesions characteristic of DM, including a heliotrope rash, shawl sign, and V-sign. She also exhibited atypical features, such as pseudoangioedema, an ovoid palatal patch, and generalized subcutaneous edema. Laboratory studies showed elevated muscle enzyme levels and positivity for anti–TIF1γ antibodies. Imaging revealed a solid–cystic pancreatic mass, which was histologically confirmed to be a solid pseudopapillary tumor. Following surgical resection, muscle enzyme levels normalized and cutaneous manifestations improved, although proximal quadriparesis persisted (Fig. 1). This case expands the spectrum of neoplasms associated with DM and highlights the relevance of atypical cutaneous manifestations and anti–TIF1γ antibodies as markers warranting surveillance for occult malignancy. The clinical improvement following tumor resection further supports a paraneoplastic association. Key Points • Atypical cutaneous findings—such as pseudoangioedema, ovoid palatal patch, and generalized subcutaneous edema—may serve as clinical indicators of paraneoplastic dermatomyositis. • The coexistence of dermatomyositis with a solid pseudopapillary pancreatic tumor represents an exceedingly rare association. • This case study underscores the significance of incorporating rare pancreatic tumours in the list of malignancies for patients diagnosed with dermatomyositis and anti-TIF1γ antibodies. • Improvement of cutaneous lesions and normalization of muscle enzymes after tumor resection reinforce the causal link between the neoplasm and dermatomyositis.