CHARACTERIZATION OF ALVEOLAR SOFT PART SARCOMA OF THE TONGUE: A CLINICO-PATHOLOGIC STUDY AND SCOPING REVIEW

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A.O. Akinyamoju¹; O.O. Gbolahan²; and B.F. Adeyemi¹

1. Department of Oral Pathology, Faculty of Dentistry, College of Medicine, University of Ibadan/University College Hospital Ibadan, Nigeria.
2. Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, College of Medicine, University of Ibadan/University College Hospital Ibadan, Nigeria.

Abstract

Background: Alveolar soft part sarcoma (ASPS) is a rare malignant soft tissue tumour. There is a dearth of literature analyzing its features on the tongue.

Objectives: This study aims to conduct a scoping review to describe the essential clinico-pathologic features, treatment modalities and outcome of previously reported tongue ASPS (TASPS) and new cases at our center.

Methods: A search of databases (PubMed, Medline, Cochrane and Google Scholar) and the internet for articles on TASPS written in English was conducted. Information extracted included clinico-pathological and demographic data. Descriptive statistics was used for analysis.

Results: A total of 49 articles were eligible for this study. In all, 81 cases were utilized. Asian studies accounted for most cases 35(43.2%) and a slight female
preponderance of 1.1 was seen. Most cases – 38 (46.9%), occurred in the 1st decade and the base of tongue was the most common location in 19 (39.6%) cases. Also, tumour metastasis was present in 14 (25.9%) cases. Transcription Factor E3 (TFE3) – 8 (24.2%) and Neuron Specific Enolase (NSE) – 8 (24.2%) were the most common immunohistochemical stains used and were both expressed 7 out of 8 cases (87.5%). Most common treatment modality was surgery and 42 (82.4%) cases managed by surgery alone were free of disease at < 5 years of follow up.

Conclusions: TASPS slightly affected the female gender and tongue base more commonly. It occurred more in the first two decades of life. Use of standard investigative tools for management will allow for better appraisal of research findings.

Keywords: Tongue; Alveolar; Soft-part; Sarcoma; Treatment outcome

Introduction

Alveolar soft part sarcoma (ASPS) is a rare malignant soft tissue tumour that accounts for about 1% of all soft tissue sarcomas.^1,2 It was first described in 1952 by Christopherson and Stewart.³ Despite numerous studies since then, the histiogenesis, biologic behavior and best treatment modality has remained debatable. The head and neck region is the favored site for ASPS in children and adolescents while the thigh and buttocks are common sites for ASPS in adults.^4-6 Also, a female predilection has been reported in cases occurring in the 1st and 2nd decades of life while a slight male preference was observed after the 3rd decade.^7-9

Presentation of ASPS is usually that of a slow growing painless mass, with a high rate of metastasis to the lungs, bone, and the brain, which could occur long after excision of the primary tumour.^2,7,10 ASPS could present clinically as a vascular lesion and magnetic resonance imaging (MRI) of the tumour with contrast enhancement is ideal to demonstrate its vascular nature^11-13 whilst differentiating it from other vascularized tumours.

Microscopically, ASPS consists of large polygonal to round cells with distinctive cell membrane, abundant eosinophilic granular cytoplasm, round to oval eccentric nuclei with prominent nucleoli which may be multiple. Neoplastic cells are characteristically disposed in nested or organoid growth pattern separated by thin fibrous septa.^6,14,15 The cells may appear non-cohesive, giving it the alveolar pattern. Those without organoid patterns have also been described as well as those with clear cytoplasm. The solid pattern is more frequently seen in pediatric cases.¹⁶ The tumour is well vascularized by delicate sinusoidal vascular channels lined by a single layer of endothelial cells. Pleomorphism and mitosis are infrequent. About 80% of ASPS have intracytoplasmic, periodic acid– schiff positive, diastase-resistant rhomboid- or rodshaped crystals.¹⁶

Furthermore, ASPS have been reported to commonly occur on the tongue in many studies, as well as in case reports and constitute 25% of all ASPS.^17-21 Also, tongue alveolar soft part sarcoma (TASPS) occurs in patients much younger than those for ASPS from other anatomical locations particularly in females.^{2, 18, 22, 23}

There are many reports describing the clinicopathologic features of ASPS.^{10, 18, 24} However, there is a dearth of literature analyzing these features in tongue tumours only, despite the tongue being a common site of presentation in the head and neck region. Therefore, it is desirable to assess the characteristics of TASPS and to assess the available treatment modalities necessary to achieve a desirable outcome in the management of this entity. This study aims to describe the essential clinico-pathologic features, treatment modalities and outcome of previously reported TASPS by conducting a scoping review along with present cases seen at the Oral Pathology Department, University College Hospital, Ibadan.