Background: Mantle cell lymphomas are aggressive, mature B-cell neoplasms characteristically showing overexpression of cyclin D1. Although lymphadenopathy is the most common presentation, involvement of extranodal sites including bone marrow, peripheral blood, liver, gastrointestinal system, and Waldeyer ring is also seen frequently. Soft tissue localization is extremely rare. It has blastoid and pleomorphic subtypes associated with aggressive course. Case description: We describe a 74-year-old man who had been diagnosed 3 years previously with "mantle cell lymphoma-blastoid type" and presented 3 months ago with a giant mass in the right lower extremity that enlarged rapidly up to 15 cm in a few months. Conclusion: We present this rare presentation, which was evaluated in favor of hemangioma before biopsy, together with the data in the literature to emphasize the need for differential diagnosis, especially in cases with a clinical history.