Cytodiagnosis of alveolar soft part sarcoma: Report of two cases with special emphasis on the first orbital lesion diagnosed by aspiration cytology

Abstract

Alveolar soft part sarcoma (ASPS) is a rare neoplasm of uncertain cell of origin. Known to occur in adolescents and young adults, this tumor usually involves the muscles and deep soft tissues of the extremities and trunk. Orbital localization is rare and not yet subjected to cytological assessment, as per our literature search. We present here two cases of ASPS diagnosed by aspiration cytology, one in the orbit and the other in the lower extremity. The cells displayed abundant clear to finely vacuolated cytoplasm, often with disrupted margins and flowing of the cytoplasmic material; prominent nucleoli and scattered bare nuclei were also seen in the background. Two close cytological differential diagnoses include metastatic renal cell carcinoma and paraganglioma. Intracytoplasmic periodic acid schiff (PAS) positive, diastase-resistant, needle-shaped crystals and corresponding rhomboid crystals with regular lattice pattern on ultrastructure are the hallmarks of this neoplasm. Due to its slowly progressive clinical course and poor outcome, preoperative diagnosis of ASPS through fine-needle aspiration cytology may be essential for deciding therapy, especially in rare and difficult locations like orbit, where adjuvant radiation may not be possible.

Alveolar soft part sarcoma: A distinct cytomorphology and characteristic TFE3 staining

“…2 On FNA biopsies, the smears show slight to moderate cellularity with some characteristic cytological features that includes: Many naked nuclei, scattered large, round to polygonal cells with prominent nucleoli and abundant granular and fragile cytoplasm. 3,4 Shabb et al found that numerous stripped tumor nuclei were a consistent cytomorphologic feature of ASPS cases and Wakely et al…”

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

“…4,5 Few cytology case reports and case series highlight the morphological features of ASPS. 1,6,7 ASPS cases also show intracytoplasmic rod-like crystalloids or inclusions, which are better highlighted on PAS-diastase staining. 4,7 However, after extensive screening, no definite crystalloids or inclusions could be found in the present case.…”

“…Few cytology case reports and case series highlight the morphological features of ASPS 1,6,7 . ASPS cases also show intracytoplasmic rod‐like crystalloids or inclusions, which are better highlighted on PAS‐diastase staining 4,7 .…”

“…Due to the cytoplasmic fragility of these cells, many bare nuclei were observed. The background shows haemorrhage, owing to the vascular nature of the tumour 6 …”

“…Paragangliomas do not involve extremities and show marked anisonucleosis without prominent nucleoli. The cells are positive for neuroendocrine markers; synaptophysin and chromogranin and show S‐100 positivity in the sustentacular cells 6 . Granular cell tumour usually present as a small incidental tumour, most commonly located in the tongue, and unlike ASPS, they have coarse cytoplasmic granules, lack fine intercellular vascularity, and are positive for S100, SOX1 and inhibin 7 …”