Minute myopericytoma of the neck: a case report with literature review and differential diagnosis.

Reports of cutaneous myopericytoma (MPC) are very rare. The author herein reports a case of minute MPC of the neck. A 56-year-old woman noticed a painful small tumor in the neck, and consulted to our hospital. Dermatologists's diagnosis is a hyperplastic lymph node. Excision of the tumor was performed. Grossly, the tumor was a sold white tumor measuring 3 × 3 × 3 mm. Microscopically, it consisted of many vascular channels and perivascular cell proliferation encased by a fibrous capsule. The vascular proliferation showed a hemangiopericytoma (HPC)-like pattern such as staghorn-like vessels. Fibrosis was not present. The HPC-like cells had vesicular nuclei and polygonal cytoplasm. No atypia is recognized. The HPC-like cells focally showed vague nodular proliferation around the vessels. Immunohistocheically, the tumor cells were negative for cytokeratin, and positive for vimentin. The vasculatures were positive for factor VIII-related antigen, CD34, and CD31. The HPC-like tumor cells were positive for α-smooth muscle actin and h-caldesmon, but negative for desmin, S100 protein, melanosome, bcl-2, CD99, and KIT. The Ki-67 labeling was 8% and p53 was negative. The pathologic diagnosis was MPC of the neck skin. The patient is now alive without recurrence 4 years after the excision. A review of the literature revealed 73 cases of MPC from 6 papers. MPC is male predominance, and the patients ages ranges from 13 to 87 years with the median of 47 years. The most common location was lower extremities followed in order by upper extremities, head and neck, and trunk. One MPC occurred within the vasculature, and 3 cases of MPC developed in the scar or trauma lesions. The prognosis after excision is good, but a very minority showed local recurrence. A differential diagnosis was also made.