Primary Cutaneous Histiocytic Sarcoma: A Rare Case

Histiocytic sarcoma is a rare malignancy composed of neoplastic cells that resemble macrophages in morphology and immunoprofile. It manifests in lymph nodes or extranodal sites, with the majority occurring in the gastrointestinal tract, central nervous system, spleen, skin, and soft tissues. Clinical manifestations depend on organ involvement, with systemic symptoms, including fever, fatigue, night sweats, weight loss, and weakness. A significant proportion of patients are diagnosed at an advanced stage, which is associated with high mortality rates. In this report, we highlight the case of an 80-year-old who displayed a subcutaneous forearm lesion. Histological evaluation confirmed the diagnosis of cutaneous histiocytic sarcoma, with tumor cells expressing CD163 and CD68. A multidisciplinary team decided on supplementary adjuvant radiotherapy, considering the unifocal presentation and complete surgical excision of the lesion. The patient remains disease-free at one-year follow-up. This case emphasizes that a unifocal and localized manifestation of the malignancy has a more favorable outcome. Although treatment protocols have not yet been standardized, recent advances in genomic profiling may offer opportunities for targeted therapies.