When the Rare Becomes Rarer: Metastasis of Epithelioid Malignant Peripheral Nerve Sheath Tumor (MPNST) to Lymph Node and Pleural Fluid.

Epithelioid malignant peripheral nerve sheath tumor (MPNST) is a rare and aggressive soft tissue sarcoma variant, seldom presenting with lymph node or pleural metastasis. We report a rare instance of a 22-year-old female with recurrent epithelioid MPNST metastasizing to cervical lymph nodes and pleural fluid-a phenomenon rarely documented in literature. Clinical history, cytomorphological assessment, and immunohistochemistry were pivotal in establishing the diagnosis. This case underscores the diagnostic complexity and extreme rarity of epithelioid MPNST metastasizing to serous cavities.