Giant Necrotic Axillary Metastasis From Pancreatic Neuroendocrine Carcinoma Treated With Palliative Resection and Breast Reconstruction: A Case Report.

Neuroendocrine tumors of the pancreas are rare and can present with atypical metastatic patterns. Axillary involvement is extremely uncommon and requires a diagnosis of exclusion. Furthermore, it can be a therapeutic challenge. We present the case of a 78-year-old woman with a medical history of arterial hypertension, type 2 diabetes mellitus, and Parkinson's disease. She was diagnosed with pancreatic carcinoma with metastatic disease to axillary nodes. The patient developed a massive necrotic axillary tumor, measuring approximately 30 × 30 cm clinically, also associated with erythema, pain, exudate, and local infection. Laboratory tests showed severe anemia (Hb 7.4 g/dL), neutrophilia (95.1%), hyponatremia (Na 132 mmol/L), and hypokalemia (K 2.3 mmol/L). Imaging (contrast-enhanced CT and angio-CT) revealed a well-defined mass displacing the pectoral, deltoid, and serratus muscles; partially compressing the brachial artery with distal recanalization; and measuring approximately 25 cm x 20 cm. Three months after the first diagnosis, the patient underwent a palliative surgery including a block resection of the axillary tumor measuring 26 × 21 × 8 cm and weighing 3000 g. Histopathology results showed a poorly differentiated metastatic neuroendocrine carcinoma with rhabdoid features, extensive necrosis throughout the whole tumor, and positive margins. Immunohistochemistry was also performed and revealed focal enolase positivity, while CD56, p53, and chromogranin were negative. Pancreatic neuroendocrine tumors usually metastasize to the liver, peritoneum, or lymph nodes. Axillary metastasis is extremely rare and has been documented in only a few cases. The presence of a large, necrotic, infected tumor in this location significantly impacts quality of life. Surgical resection, although not curative, may provide substantial pain relief, control local complications, reduce infectious sequelae, and improve quality of life. This particular case highlights an uncommon metastatic site of pancreatic neuroendocrine carcinoma. Awareness of atypical metastatic patterns is essential for more precocious management, and surgical resection can provide substantial palliative benefit in selected patients.