Mesenteric Leiomyosarcoma masquerading as a generalized weakness: A rare case report

Mesenteric leiomyosarcoma (M-LMS) is a rare malignancy arising from smooth muscle cells that often presents with nonspecific symptoms, making early diagnosis challenging. While LMS are known to develop in retroperitoneal or pelvic regions, their occurrence in the mesentery is exceptionally uncommon. This case report discusses the presentation, diagnosis, and management of mesenteric root LMS in a 40-year-old female, highlights the complexities associated with this rare disease. The patient presented with generalized weakness for five years and lower abdominal pain for one year. Physical examination revealed pallor, and blood tests revealed anemia. Imaging studies revealed a large lobulated mass in the abdomen, which was surgically resected. Histopathological analysis confirmed the diagnosis of a high-grade spindle cell tumor, specifically M-LMS, with negative CD117 staining and positive smooth muscle actin (SMA) staining. The patient underwent completion radical surgery with resection and anastomosis of the small intestine and was treated with adjuvant chemotherapy. The patient demonstrated excellent clinical response and remained disease-free for 10 years following surgery and chemotherapy. Mesenteric M-LMS is a rare subtype of soft tissue sarcoma (STS) that is often asymptomatic until advanced stages. The diagnosis is often delayed owing to its nonspecific presentation, such as abdominal pain, weakness, or anemia, as observed in this case. Histopathologically, LMS is characterized by spindle cells arranged in fascicles, displaying nuclear pleomorphism, high mitotic activity, and areas of necrosis. Immunohistochemistry (IHC) is crucial for distinguishing LMS from other spindle cell tumors, such as gastrointestinal stromal tumors (GISTs), which express CD117 and DOG1. In contrast, LMS stains positive for smooth muscle markers such as desmin, caldesmon, and SMA. Genetic mutations, such as the loss of the tumor suppressors TP53 and RB1 and the dysregulation of the PI3K/AKT/mTOR pathway, play critical roles in the pathogenesis of LMS. Surgical resection remains the mainstay of treatment, with adjuvant chemotherapy showing modest efficacy in preventing recurrence. However, high-grade tumors and large tumors pose significant risks for recurrence and metastasis. M-LMS is a rare but aggressive neoplasm with a poor prognosis if not treated aggressively. Early recognition, radical surgical resection, and adjuvant chemotherapy are essential for long-term survival. This case highlights the importance of a multidisciplinary approach, individualized treatment plans, and regular follow-up for the early detection of recurrence.