MULTIFOCAL PULMONARY GRANULAR CELL TUMOR

Abstract

TOPIC: Lung Cancer TYPE: Medical Student/Resident Case Reports INTRODUCTION: Granular cell tumors, also known as Abrikossoff tumors, are a rare group of Schwannian neoplasms typically found in the skin and tongue, but also occur in the lung. Granularity of the cells is due to accumulation of secondary lysosomes in the cytoplasm. Only 0.5-2% of pulmonary granular cell tumors (pGCT) are malignant, but some benign cases show similar behavior. Here, we describe a diagnostically challenging case of multifocal pGCT. CASE PRESENTATION: A 48-year old male with history of asthma, chronic obstructive pulmonary disease, hypertension, and alcoholic steatohepatitis presented for evaluation of a right lung mass found on chest X-ray 5 years ago. He endorsed progressive dyspnea poorly controlled with beclomethasone and albuterol inhalers. He had history of tobacco smoking with 31 pack-years, as well as alcohol abuse. He worked in a shipyard for 3 years with exposure to asbestos and welding fumes. Computed tomography of the chest showed a 4.1-cm solid mass in the right lower lobe, as well as a 1.1-cm endobronchial lesion in the right bronchus intermedius, multiple left lower lobe lesions, and mediastinal lymphadenopathy. Spirometry showed moderate obstructive disease with bronchodilator response. Biopsies of lower lobe and tracheal mucosal lesions obtained by bronchoscopy revealed sheets of epithelioid cells with abundant eosinophilic granular cytoplasm and small uniform nuclei consistent with pGCT. There was no evidence of necrosis or increased mitotic figures to suggest malignancy. Immunostaining was positive for S100, CD68, SOX10, inhibin, and PAS. He was referred to Interventional Pulmonology for laser debulking and endobronchial stenting. DISCUSSION: Determining whether pGCTs are malignant or benign can be challenging. Both types occur in all age groups. Both can cause dyspnea, cough, and pleuritic chest pain. Large tumor size is not predictive, as many malignant pGCT's are <4 cm at time of diagnosis. Additionally, 20% of benign pGCTs have multiple lung lesions. However, the presence of extrapulmonary metastases is diagnostic of malignancy. Malignant pGCTs also show 3 or more histologic features of the Fanburg-Smith criteria, including necrosis, spindling, pleomorphism, vesicular nuclei with large nucleoli, high nuclear/cytoplasmic ratio, and increased mitotic activity. Positive p53 or Ki67 immunostaining can indicate malignancy in indeterminate cases. Management of benign pGCTs is surgical. Small tumors <1.0 cm may be removed by bronchoscopic extirpation, laser therapy, or sleeve resection. Larger tumors are resected surgically. Prognosis for benign pGCT is good (2-8% recurrence) if complete margin-free removal is achieved. CONCLUSIONS: Malignant and benign pGCTs share many features that make them difficult to differentiate. Absence of extrapulmonary metastases, Fanburg-Smith criteria, and specific immunostaining helps rule out malignancy in cases with multifocal lung lesions. REFERENCE #1: Jiang M, Anderson T, Nwogu C, Tan D. Pulmonary malignant granular cell tumor. World J Surg Oncol. 2003;1(1):22. Published 2003 Oct 21. doi:10.1186/1477-7819-1-22. REFERENCE #2: Fanburg-Smith JC, Meis-Kindblom JM, Fante R, Kindblom LG. Malignant granular cell tumor of soft tissue. Diagnostic criteria and clinicopathologic correlation. Am J Surg Pathol. 1998;22:779–794. doi: 10.1097/00000478-199807000-00001. REFERENCE #3: Khansur T, Balducci L, Tavassoli M. Granular cell tumor: clinical spectrum of the benign and malignant entity. Cancer. 1987;60:220–222. DISCLOSURES: No relevant relationships by Ramiz Fargo, source=Web Response No relevant relationships by Joseph Mak, source=Admin input No relevant relationships by Bryce Mikel, source=Web Response