Massive localized lymphedema (MLL) is an uncommon benign skin lesion typically presenting with prominent edema and vascular proliferation in the adipose tissue of lower limbs. When rarely occurring in scrotum, it instead is characterized by a striking proliferation of dermal smooth muscle bundles mimicking acquired smooth muscle hamartoma of dartos. The authors report a rare case of scrotal MLL. A 57-year-old obese man with a history of previous surgery for rectal adenocarcinoma, 20 years earlier, presented with progressive nodular enlargement of the scrotum for 2 years, causing discomfort, difficulty in ambulation, and cosmetic problems. The preoperative radiographic investigation revealed thickening of the scrotal wall with multiple soft-tissue nodules. The patient underwent a wide excision of the scrotal wall, perineum, and penile skin. The pathological examination showed a scrotal MLL associated with well-differentiated squamous cell carcinoma. The authors speculate that prior radiotherapy and surgery together with morbid obesity led to long-standing lymphedema that triggered the proliferation of smooth muscle cells, chronic epidermal change, and finally squamous cell carcinoma.