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.
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.
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
Three dimensional reconstructed CT image demonstrating an endobronchial soft tissue abnormality.
Bronchoscopic evaluation showed an endobronchial nodule involving the left mainstem bronchus (Figure
Bronchoscopic image demonstrating an endobronchial nodule at the left mainstem bronchus.
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 (DakoCytomation Autostainer, Denmark). Antibodies used are shown in Table
Panel of antibodies used for immunohistochemical analysis
Antibody | Clone | Company | Antigen retrieval | Dilution |
---|---|---|---|---|
Cytokeratin | AE1/AE3 | Dako | Steam | Prediluted |
Desmin | DE-R-11 | Dako | Steam | Prediluted |
EMA | Monoclonal | Dako | Citrate buffer | Prediluted |
CD34 | QBEnd 10 | Dako | Steam | |
SMA | 1A4 | Dako | None | Prediluted |
S100 | Polyclonal | Dako | Steam | Prediluted |
MyoD1 | 5.8A | Dako | Steam | |
CD117 | T595 | Biogenex | Steam | Prediluted |
Claudin-1 | Polyclonal | Zymed | Steam | Prediluted |
Sections of bronchial biopsies demonstrated a cellular proliferation that was situated in submucosal tissue beneath histologically unremarkable bronchial mucosa (Figure
Spindle cell proliferation situated beneath benign bronchial mucosa. Hematoxylin and eosin.
Photomicrograph demonstrating a bland spindle cell proliferation with a collagenized stroma. Hematoxylin and eosin.
Spindle cells staining positively with claudin-1.
Spindle cells staining positively with epithelial membrane antigen (EMA).
Perineurioma is a rare benign tumor composed exclusively of perineurial cells. First reported by Lazarus et al., it is typically characterized by an unencapsulated yet circumscribed proliferation of bland spindle cells arranged in a storiform pattern within a variably collagenized stroma. Ultrastructural analysis demonstrates thin bipolar cytoplasmic processes, junctional complexes, and smooth vesicles [
Soft tissue and intraneural subtypes of perineurioma have been described. Soft tissue perineurioma itself has three types. The sclerosing variant of soft tissue perineurioma presents as a small painless dermal or subcutaneous mass involving the digits or palms of young adults [
The second subtype of perineurioma is the intraneural perineurioma, formerly referred to as localized hypertrophic neuropathy [
Immunohistochemistry is pivotal in the accurate classification of perineurioma. The majority of perineuriomas express EMA with variable expression of CD34 and smooth muscle actin (SMA). Glut-1 is a human red blood cell glucose transporter which is expressed in perineurial cells. In their study, Yamaguchi et al. demonstrated strong reactivity for glut-1 in the five cases they reported [
The clonal nature of intraneural perineurioma has been confirmed by demonstrating a lack of all or a portion of chromosome 22 [
Perineurioma is thought to represent a benign entity. Hirose et al. reviewed 121 malignant peripheral nerve sheath tumors (MPNSTs) from their files looking for cases having perineurial differentiation [
The case presented in this paper represents an endobronchial perineurioma. While perineurioma usually occurs in the skin and superficial soft tissues, it has been reported in unusual sites and should be considered in the differential diagnosis of spindle cell lesions in any location.
The claudin-1 immunostain was performed at Emory University and the diagnosis of perineurioma was rendered by Dr. Sharon W Weiss, Professor of Pathology and Laboratory Medicine at Emory University School of Medicine.