Endobronchial Perineurioma: An Unusual Soft Tissue Lesion in an Unreported Location

We report the first case of an endobronchial perineurioma, a rare benign neoplasm typically occurring in soft tissue. A 53-year-old nonsmoking female presented with a three-month history of persistent bronchitis. A CT scan followed by bronchoscopy demonstrated an endobronchial lesion involving the left mainstem bronchus. Removal of the lesion by bronchoscopy was accomplished. The tumor was composed of bland spindle cells in a variably collagenized stroma. These cells had long cytoplasmic processes. No mitotic activity or necrosis was observed. Neoplastic cells were immunoreactive for epithelial membrane antigen (EMA), CD34, and claudin-1. Smooth muscle actin (SMA), desmin, and S-100 immunostains were all negative. Based on the morphologic appearance and immunophenotype, a diagnosis of perineurioma was rendered. 1. Introduction Perineuriomas are rare benign neoplasms representing a proliferation of perineurial cells. Two distinct subtypes are recognized and include soft tissue perineurioma and intraneural perineurioma. Perineuriomas most commonly occur in the dermis and subcutis of the limbs or trunk, but other locations have been reported. Herein, we describe the first case of soft tissue perineurioma occurring in an endobronchial location. 2. Case Report A 53-year-old nonsmoking female presented to her primary care physician with a three-month history of a nonresolving upper respiratory infection. A chest-computed tomographic (CT) scan demonstrated a 6？mm endobronchial soft tissue abnormality with slight contrast enhancement at the periphery involving the left mainstem bronchus. Three-dimensional reconstruction of CT images showed similar findings (Figure 1). Figure 1: Three dimensional reconstructed CT image demonstrating an endobronchial soft tissue abnormality. Bronchoscopic evaluation showed an endobronchial nodule involving the left mainstem bronchus (Figure 2). The lesion was removed during a subsequent bronchoscopy. A CT scan, including three dimensional bronchial reconstruction performed after a six month interval, showed no evidence of a residual endobronchial lesion. The patient is well one year following initial presentation. Figure 2: Bronchoscopic image demonstrating an endobronchial nodule at the left mainstem bronchus. 3. Materials and Methods Bronchoscopic biopsies were fixed in 10% neutral buffered formalin then subjected to routine processing and paraffin embedding. Sections were stained with hematoxylin and eosin. Immunohistochemical stains were performed on paraffin embedded tissue using the avidin biotin peroxidase complex method