Rectus Sheath Hematoma as a Cutaneous Manifestation of Essential Thrombocythemia

Rectus sheath hematoma (RSH) is a rare cause of acute abdominal pain that is often associated with trauma, anticoagulant therapy, or coagulopathy. We present a unique case of an RSH as a cutaneous manifestation of essential thrombocythemia (ET), which is a myeloproliferative neoplasm characterized by thrombotic and hemorrhagic complications. A 66-year-old female patient presented with acute lower abdominal pain, a subcutaneous mass, and overlying skin ecchymosis. Imaging confirmed a significant RSH. Laboratory tests revealed severe anemia and marked thrombocytosis. Further evaluations, including bone marrow biopsy and genetic testing, revealed ET with a <i>CALR</i> mutation. RSH was managed conservatively, and cytoreductive therapy comprising hydroxyurea was administered for ET, resulting in resolution of the hematoma and improvement in hematological parameters. This case highlights the necessity of considering hematological disorders when patients present with spontaneous hematomas. Prompt diagnosis and effective management of both the hematoma and ET were achieved, demonstrating that timely recognition and appropriate treatment are important to improving patient outcomes.