Alveolar Soft Part Sarcoma of Hypopharynx; A Case Report

Abstract

Alveolar soft part sarcoma (ASPS) is an aggressive soft-tissue malignancy, notorious for its metastasis to other tissues. A considerable number of cases in the head and neck have been reported but not in the hypopharynx. We describe a 31-year-old man with an incidental finding of a hypopharyngeal mass. Flexible laryngoscopy revealed a fleshy mass 2 × 2 cm2 originating from the left hypopharynx and overlying the epiglottis. Computed tomography scan demonstrated a soft tissue mass in the left wall of the oropharynx measuring about 2.2 × 1.8 cm2, projecting into the hypopharyngeal air space. Magnetic resonance imaging showed a significant thickening of the left hypopharyngeal wall forming a mass lesion occupying the left pyriform sinus and abutting the left aryepiglottic fold. Histopathology indicated that tumor cells were polygonal and epithelioid, with abundant eosinophilic to clear flocculent cytoplasm, eccentric nuclei, and prominent nucleoli. The tumor was positive for smooth muscle actin with rare cells staining for Human Melanoma Black (HMB45). Fluorescence in situ hybridization for transcription factor E3 was also performed and supported the above diagnosis. Our study reports the first case of ASPS in the hypopharynx.

Alveolar soft part sarcoma: A case report and review of the literature

“…On MRI, ASPS shows an abundant solid component, while a vascular malformation has exclusively vascular components. 2 However, this differentiation was not evident in the present case. ASPS is associated with an unbalanced translocation, der(17)t(X;17)(p11;q25), which results in the formation of a fusion gene, ASPL-TFE3, and aberrant expression of transcription factor TFE3 protein, which can be detected by real-time polymerase chain reaction, which is more sensitive and specific than IHC.…”

“…A typical arteriovenous malformation shows rapid draining of contrast agent due to high‐flow shunting, whereas ASPS shows a delayed washout pattern and intense solid tumour staining. On MRI, ASPS shows an abundant solid component, while a vascular malformation has exclusively vascular components 2 . However, this differentiation was not evident in the present case.…”

“…It has a female preponderance and a propensity to involve head and neck region and extremities in children and adults, respectively. The tumour has metastatic potential and the common sites are lungs, brain, and bone 2 . Tumour in the extremities is associated with metastases in about 20%‐40% of cases at the time of diagnosis 3 .…”

“…The tumour has metastatic potential and the common sites are lungs, brain, and bone. 2 Tumour in the extremities is associated with metastases in about 20%-40% of cases at the time of diagnosis. 3 ASPS is a richly vascular tumour, and the same is reflected in its imaging findings.…”