Case report: superficial kaposiform hemangioendothelioma without the Kasabach-Merritt phenomenon.

Kaposiform hemangioendothelioma (KHE) is a rare intermediate-grade malignant vascular tumor that is frequently associated with the Kasabach-Merritt phenomenon (KMP). Cases without KMP are less common and, therefore, prone to misdiagnosis. We report a case of superficial KHE in a 6-month-old male infant without associated KMP. Magnetic resonance imaging revealed a poorly demarcated lesion with T1 hypointensity and T2 hyperintensity, demonstrating marked enhancement and an arterial flow void. The patient was hospitalized because KHE was suspected and received a single course of intralesional pingyangmycin therapy. One week later, histopathological examination showed proliferating spindle-shaped endothelial cells in a glomeruloid pattern. The immunohistochemical results revealed CD31 and CD34 positivity and GLUT1 and D2-40 negativity. GLUT1 negativity helped exclude infantile hemangioma, whereas D2-40 negativity ruled out lymphatic malformation. Upon confirming KHE diagnosis, we initiated a combined sirolimus and prednisone treatment. At the 3-month follow-up, clinical observation showed regression of the lesion, prompting prednisone discontinuation while continuing sirolimus maintenance therapy. In this report, we also discuss the clinical manifestations, imaging features, histopathological characteristics, and treatment options for this KHE subtype and review relevant literature. This case highlights the diagnostic features and therapeutic considerations of superficial KHE without KMP, emphasizing the importance of multidisciplinary evaluation.