Fine‐needle aspiration of alveolar soft part sarcoma: Histologic correlation and aberrant CD68 expression

Abstract

Alveolar soft part sarcoma is a rare highly malignant neoplasm of the soft tissue and usually occurs in the lower extremities of children and young adults. We report two cases of alveolar soft part sarcoma: a 24-year-old Latino man with a 10-cm neck mass and a 56-year-old Latino woman with a recurring thigh mass. Fine-needle aspiration and a core biopsy were performed on both, which was followed by tumor resection on the man. The smears displayed numerous loosely cohesive or single large cells with abundant granular cytoplasm, round nuclei, vesicular chromatin, and occasional prominent nucleoli. Periodic and Schiff (PAS)-positive, diastaseresistant rhomboid, or needle-shaped crystals were present. Both tumors had diffuse and strong nuclear TFE3 expression and aberrant cytoplasmic CD68 expression. Fluorescence in situ hybridization analysis was performed in the first case, which detected a characteristic translocation t(X;17)(p11;q25). The diagnosis of alveolar soft part sarcoma was rendered in both cases.Herein, we present the cytology, histology, immunohistochemistry, and molecular findings and discuss the differential diagnosis. K E Y W O R D S aberrant CD 68 expression, alveolar soft part sarcoma, crystal, fine-needle aspiration, TFE3 expression 1 | INTRODUCTION Alveolar soft part sarcoma (ASPS) is a rare highly malignant neoplasm and accounts for 0.2%-0.9% of the soft tissue sarcoma. 1 A female predominance is seen in patients younger than 30 years. 2,3 ASPS usually arises from deep soft tissue of the thigh or buttock. It usually affects the head and neck region such as tongue or orbit in infants and children. 2 Primary ASPS of visceral organs has also been reported. 4 ASPS usually presents as a solitary, painless, slowly growing soft tissue mass. Rarely, it may have an aggressive course. 5 The local recurrence rate is 20%-30%. 6 The most common metastatic sites are the brain and the lung. Current metastases in the brain and lung occur in approximately 30% of the patients. Prognosis is poor with survival of 12-17 months. 7,8 Cytogenetic study of ASPS has shown the unbalanced translocation der(17)t(X;17)(p11;q25) producing the fusion of the N-terminal region of the alveolar soft part sarcoma locus (ASPL) gene on17q25 to the C-terminal of transcription factor E3 (TFE3) on Xp11. This results in two types of fusion transcripts (ASPL-TFE3 types 1 and 2), which lead to tumorigenesis by transcriptional deregulation. 9 The overexpressed fusion protein can be detected by immunohistochemistry (IHC) with anti-TFE3 antibody. 10,11 There is limited published literature regarding the cytological features of ASPS. Extremely rare cases with diffuse immunoreactivity for CD68 in ASPS have been reported. 12,13 2 | CASE REPORTS 2.1 | Clinical history Case 1: The patient was a 24-year-old Latino man with a history of intellectual disability due to cerebral palsy presented with a posterior neck mass for a year. The mass had been enlarging over a few months. Physical examination revealed a 10 cm well-circumscribed soft mass arising...

Transthoracic Fine-Needle Aspiration Cytology of Pulmonary Spindle and Mesenchymal Neoplasms: A Pandora’s Box

“…Only three cases of primary pulmonary ASPS have been reported till date [30]. This is the first case reporting its cytomorphology, while the existing literature on the cytomorphology of ASPS is already extremely limited [31,32]. Cells with large, vesicular nuclei, prominent eosinophilic macronucleoli, and abundant cytoplasm seen in ASPS (Fig.…”

Revisiting cytomorphology, including unusual features and clinical scenarios of 8 cases of alveolar soft part sarcoma with TFE3 immunohistochemical staining in 7 cases

“…Paragangliomas also display TFE3 positivity, in addition to markers of neuroendocrine differentiation 4 . While Nambirajan et al 11 reported an aberrant CD10 immunoexpression in a case of metastatic ASPS, Xu et al 12 reported aberrant CD68 immunopositivity in 2 cases of ASPS, diagnosed on cytology, including the characteristic t(X;17)(p11;q25) translocation in a single case. In one of the earlier reported cases of translocation‐related RCC, tumour cells were found to be positive for CD10 and TFE3.…”

“…[5][6][7][8][9][10] Alveolar soft part sarcoma is known to be associated with some uncommon clinical and morphological features, along with variable immunohistochemical staining results. [11][12][13] Apart from a few reported cases, there is no documented series on FNAC of ASPS confirmed with TFE3 immunohistochemical staining.…”