1

Introduction

Alveolar soft part sarcoma (ASPS) is a rare malignancy accounting for 0.2% to 0.9% of soft tissue sarcomas . This entity was first described in the literature by Christopherson et al. in 1952 after encountering several unique histologic entities during a 17 year period . ASPS often occur in children and adolescents in the age range of 15 to 35 years . Frequent locations for presentation include the extremities, trunk, and head and neck region. 25% of reported ASPS cases occur in the head and neck region with the most common locations being the tongue and orbit . Our literature review only identified 5 cases of ASPS originating in the larynx . This case report provides a description, our treatment approach, and review of this rare malignancy in this atypical location.

2

Case report

The patient is a 23 year-old-male who presented with a 4-year history of progressive hoarseness. He denied any other associated symptoms including dysphagia or pain. Flexible nasolaryngoscopy revealed a large left sided submucosal mass occupying the entire left hemilarynx with bowing of the ipsilateral vocal cord ( Fig. 1 ). Computer tomography (CT) showed a well-circumscribed non-cystic mass filling the left transglottic space with extension into the infraglottis. The mass abutted the arytenoid and thyroid cartilage but showed no obvious cartilage infiltration ( Fig. 2 ). A biopsy of the mass was obtained, which, on histology, showed neoplastic cells with abundant eosinophilic to clear cytoplasm within vascular spaces ( Fig. 3 ). Immunostains for various markers including cytokeratins, PAX-8, chromogranin, synaptophysin, S100, vimentin, and HMB-45 were negative. Immunostain for transcription factor E3 (TFE3) and cathepsin K were positive in the tumor cells. Given the histologic findings and immunostaining results, the differential diagnosis included metastatic translocation renal cell carcinoma (RCC) and ASPS. Because of the entirely intravascular location of the tumor on initial biopsy and the rarity of ASPS arising in the larynx, metastatic translocation RCC was initially favored.

Flexible nasolaryngoscopy demonstrating a large left sided submucosal mass occupying the entire left hemilarynx.

a) Axial CT showing left glottic mass extending to the anterior margin of the left arytenoid and abutting the left thyroid cartilage b) Coronal CT showing mass extending from the left supraglottis down to the superior margin of the left cricoid cartilage. Dimensions were 2.5 cm craniocaudal × 1.5 cm transverse × 1.8 cm anteroposterioly.

H&E stain, 400 ×. The tumor on initial biopsy is entirely intravascular and comprised of large cells with abundant eosinophilic to clear cytoplasm with enlarged, atypical nuclei. Prominent nucleoli line, and in some areas fill, the pseudoalveolar spaces.

Based on the differential diagnosis, the patient underwent extensive malignancy work-up imaging including CT abdomen and chest, magnetic resonance imaging (MRI) brain and kidney, and full body positron emission tomography (PET) showing no evidence of other malignancy, which lead to the diagnosis of primary ASPS of the larynx. The patient underwent a combined transoral and open approach vertical partial laryngectomy, which included 2 mm of the anterior contralateral glottis, ipsilateral glottis, and supraglottis including the arytenoid and thyroid cartilage. A CO ₂ laser was used to perform precise endoscopic cuts around the tumor along the glottis. Due to the size of the tumor an open approach was chosen to then remove the tumor en bloc. A strap muscle flap was used for laryngeal reconstruction and to recreate a neoglottis. Pathology revealed that 5 mm margins were achieved. Histologic examination of the partial laryngectomy specimen showed features of ASPS ( Fig. 3 b). No postoperative adjuvant therapy was done. The patient was able to be successfully decannulated within 3 months with normal breathing on exertion and normal swallow function. His voice function has been excellent considering the extent of his partial laryngectomy and he has been disease free since his surgery.

2

Case report

The patient is a 23 year-old-male who presented with a 4-year history of progressive hoarseness. He denied any other associated symptoms including dysphagia or pain. Flexible nasolaryngoscopy revealed a large left sided submucosal mass occupying the entire left hemilarynx with bowing of the ipsilateral vocal cord ( Fig. 1 ). Computer tomography (CT) showed a well-circumscribed non-cystic mass filling the left transglottic space with extension into the infraglottis. The mass abutted the arytenoid and thyroid cartilage but showed no obvious cartilage infiltration ( Fig. 2 ). A biopsy of the mass was obtained, which, on histology, showed neoplastic cells with abundant eosinophilic to clear cytoplasm within vascular spaces ( Fig. 3 ). Immunostains for various markers including cytokeratins, PAX-8, chromogranin, synaptophysin, S100, vimentin, and HMB-45 were negative. Immunostain for transcription factor E3 (TFE3) and cathepsin K were positive in the tumor cells. Given the histologic findings and immunostaining results, the differential diagnosis included metastatic translocation renal cell carcinoma (RCC) and ASPS. Because of the entirely intravascular location of the tumor on initial biopsy and the rarity of ASPS arising in the larynx, metastatic translocation RCC was initially favored.

Flexible nasolaryngoscopy demonstrating a large left sided submucosal mass occupying the entire left hemilarynx.

a) Axial CT showing left glottic mass extending to the anterior margin of the left arytenoid and abutting the left thyroid cartilage b) Coronal CT showing mass extending from the left supraglottis down to the superior margin of the left cricoid cartilage. Dimensions were 2.5 cm craniocaudal × 1.5 cm transverse × 1.8 cm anteroposterioly.

H&E stain, 400 ×. The tumor on initial biopsy is entirely intravascular and comprised of large cells with abundant eosinophilic to clear cytoplasm with enlarged, atypical nuclei. Prominent nucleoli line, and in some areas fill, the pseudoalveolar spaces.

Based on the differential diagnosis, the patient underwent extensive malignancy work-up imaging including CT abdomen and chest, magnetic resonance imaging (MRI) brain and kidney, and full body positron emission tomography (PET) showing no evidence of other malignancy, which lead to the diagnosis of primary ASPS of the larynx. The patient underwent a combined transoral and open approach vertical partial laryngectomy, which included 2 mm of the anterior contralateral glottis, ipsilateral glottis, and supraglottis including the arytenoid and thyroid cartilage. A CO ₂ laser was used to perform precise endoscopic cuts around the tumor along the glottis. Due to the size of the tumor an open approach was chosen to then remove the tumor en bloc. A strap muscle flap was used for laryngeal reconstruction and to recreate a neoglottis. Pathology revealed that 5 mm margins were achieved. Histologic examination of the partial laryngectomy specimen showed features of ASPS ( Fig. 3 b). No postoperative adjuvant therapy was done. The patient was able to be successfully decannulated within 3 months with normal breathing on exertion and normal swallow function. His voice function has been excellent considering the extent of his partial laryngectomy and he has been disease free since his surgery.