Lung Images: Primary Pulmonary Hemangiopericytoma

Abstract

A 43-year-old woman presented with cough and a 6.5 9 5cm homogeneous left lung mass on a chest roentgenogram (Fig. 1). Computed tomography of the thorax revealed a 5.5 9 5.5-cm heterogeneous mass located between the upper and lower lobe bronchi of the left lung (Fig. 2). We performed thoracotomy and a 8 9 4-cm mass between the upper and lower lobes of left lung was detected. The mass was solid and noncystic. A diagnosis of hamartoma was made by frozen section. It was removed with its capsule. Severe bleeding occurred during resection. Ligation of the bleeding artery branch stopped the bleeding. She has remained asymptomatic during the 15 months of followup. On histopathologic examination, the tumor was macroscopically defined as grey-white tissue with a lobulated surface, 6.5 9 5.5 9 4.5 cm in size. Microscopically, in the stroma between the veins there was spindle cell proliferation that did not show distinctive cytologic atypicality. These spindle cells were positively stained with CD34 and C-KIT. The vein structures were CD31-positive. Vein walls were stained with actin upon which characteristic vascular structures with stag horn configuration diagnosed the mass as primary pulmonary hemangiopericytoma (Fig. 3). Hemangiopericytoma is a rare form of sarcoma that originates from the pericytes that surround the capillary membrane [1]. The age range is wide and there is an equal distribution among males and females. The symptoms are usually cough, hemoptysis, and chest pain. The preoperative diagnosis is difficult because of the lack of specific clinical symptoms and radiologic findings. However, paraneoplastic syndromes such as osteoarthropathy and hypoglycemia may appear in relation to primary pulmonary hemangiopericytoma. During surgery a frozen section will be useful in determining the existence of malignancy. The histologic findings consist of multiple mesenchymal tumors, including hemangiopericytoma. Hemangiopericytoma is surrounded by capsules or pseudocapsules and radiologic investigation of the mass reveals clear-cut borders. Also, immunohistochemical studies can be helpful for the accurate diagnosis. Malignancy is usually manifested as