Myopericytoma Imitating Subcutaneous Melanoma Metastasis: Ultrasound Diagnosis

Myopericytomas (MPs) are rare benign tumors predominantly seen in young women, with fewer than 200 cases reported in medical literature, leading to frequent misdiagnosis. While histological examination is the gold standard for diagnosis, ultrasound imaging serves as a valuable tool for diagnostic guidance and surgical management. We present a case involving a 58-year-old woman with a history of vulvar melanoma, characterized by a Breslow’s thickness of 13 mm and left inguinal lymph node involvement. At the time of presentation, she was undergoing proton therapy targeting regional pelvic lymph nodes and was under clinical and ultrasound monitoring. The patient was referred to our Dermatology Department to assess a subcutaneous nodular lesion on her right wrist, which had developed a bluish discoloration over six weeks. Ultrasound examination, utilizing various linear probes, revealed a well-defined, non-encapsulated, hypoechoic lesion in the dermal-subcutaneous layer, exhibiting posterior acoustic enhancement. Doppler imaging indicated intense peripheral vascularity suggestive of a vascular-origin tumor. Spectral Doppler analysis demonstrated a biphasic waveform with a peak systolic velocity of 7 cm/s and a resistive index of 0.68. Additionally, shear wave elastography provided a median value of 3.5 m/s and 31.71 kPa. Given the clinical suspicion of malignancy, surgical excision was performed. Pathological examination confirmed the diagnosis of MP, showing peripheral fibrosis and oval-shaped cells with eosinophilic cytoplasm, indicative of concentric vascular growth. Immunohistochemical staining further supported the diagnosis, highlighting the utility of ultrasound in differentiating myopericytomas from other lesions in patients with a history of malignancy.