Eruptive Cutaneous Metastatic Leiomyosarcoma

Introduction: Leiomyosarcomas are malignant tumors of smooth muscle origin that infrequently involve the skin. Cutaneous metastases are rare and typically arise from retroperitoneal, uterine, or vascular primaries. We report a case of eruptive cutaneous leiomyosarcoma metastases occurring over two decades after excision of a primary subcutaneous leiomyosarcoma, representing an unusually long latency period and atypical metastatic pattern. Case Presentation: An 85-year-old Black man presented with several months of pruritic, painful, firm nodules on the scalp, right palm, and left shoulder. His history included a subcutaneous high-grade leiomyosarcoma of the right forearm excised with negative margins 26 years earlier and an incidentally discovered hepatic mass five years prior to presentation. Biopsies of the cutaneous nodules revealed atypical spindle cell proliferations positive for smooth muscle actin and desmin, consistent with leiomyosarcoma. PET imaging demonstrated an infiltrative hepatic mass invading the right kidney and numerous pulmonary and adrenal metastases. Histopathologic correlation confirmed metastatic leiomyosarcoma involving the liver and skin. The patient elected palliative gemcitabine monotherapy. Discussion: Cutaneous metastases from leiomyosarcoma are uncommon and typically signify advanced disease. The clinical and pathologic findings in this case suggest metastatic spread from the original subcutaneous tumor to the liver, which subsequently re-metastasized to the skin. Conclusion: This case underscores the potential for very late visceral and cutaneous metastases in leiomyosarcoma and highlights the need for ongoing clinical vigilance, even decades after initial treatment.