Lower li1mb mesenchymal hamartoma masquerading as hemangioma: a case report of AA2 atypical presentation and diagnostic challenges.

Introduction and importance: Hamartomas are abnormal growths that consist of various types of mesenchymal tissues, including cartilage, fat, connective tissue, and smooth muscle. These tumors can occur in almost any organ system within the body. While head and neck hamartomas have been frequently documented, cases involving the lower limbs are relatively rare. However, a unique instance of a mesenchymal hamartoma located in the leg has recently emerged. Case presentation: A 30-year-old woman presented with a painless, gradually growing swelling on her left leg, diagnosed as a subcutaneous hemangioma preoperatively. Despite unsuccessful propranolol treatment, surgical excision revealed a mesenchymal hamartoma. Postoperative examination confirmed the diagnosis, and the patient recovered smoothly without recurrence after a week of hospitalization. Clinical discussion: Cutaneous mesenchymal hamartomas are benign tissue growths with unknown etiology, associated with syndromes like Cowden and Peutz-Jeghers. Smooth muscle hamartoma can be acquired after skin trauma. Hemartoma can be misdiagnosed as hemangiomas. Cutaneous mesenchymal hamartomas presents as painless swellings in various locations, occasionally in adulthood. Differential diagnoses include lipomas and fibromas. Surgical excision is recommended for symptomatic cases to prevent recurrence. Conclusion: This case highlights the atypical presentation of the hamartoma and emphasizes the importance of accurate diagnosis and management.