Metastatic alveolar soft part sarcoma of the lung: Metastatic alveolar soft part sarcoma of the lung‐a morphologic pitfall on cytology and aberrant CD10 expression on histology

Abstract

Alveolar soft part sarcoma (ASPS) is a rare aggressive soft tissue sarcoma of young adults, typically arising in the deep soft tissue of lower extremities. Although cytomorphology is characteristic enough for an accurate diagnosis in typical clinical scenarios, problems arise when it occurs in older patients, atypical sites, or in primary evaluation at metastatic sites. A 48-year-old smoker presented with breathlessness and headache for 2 months. Imaging showed a heterogeneous enhancing lesion of 6 cm × 6 cm in right middle lobe of lung, smaller miliary nodules in bilateral lungs, multiple bilateral cerebral lesions, and a mass of 3 cm × 3 cm in the left thigh. Primary lung carcinoma with brain and thigh metastases was the clinical diagnosis. Fine-needle aspiration smears of the lung lesion showed cohesive fragments of large cells with a prominent traversing branching capillary network and discohesion at periphery resulting in a pseudo-papillary appearance. Tumor cells had fine granular to vacuolated cytoplasm, frayed borders, and prominent nucleoli. Trucut biopsy from the same showed a tumor arranged in nests composed of large polygonal cells, immunopositive for CD10. Possibility of metastatic renal cell carcinoma (RCC) was offered. Abdominal imaging was, however, normal. Core biopsy from thigh showed a similar tumor, immunonegative for epithelial markers, with cytoplasmic periodic-acid-schiff positive rhomboid crystals, clinching the final diagnosis of ASPS with lung and brain metastases. There is considerable morphological and immunohistochemical overlap between ASPS and RCC. Bare nuclei on air dried smears, binucleation, metachromatic basement membrane material are subtle pointers toward ASPS.

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

“…This morphologic feature has been earlier reported in isolated cases by some authors. 5,9,11,13 The other unusual features were intra- was helpful in ruling out ASPS in that case. 24 Additionally, PAX8 negativity in 2 cases (Cases 3 and 8) was useful in ruling out RCC.…”

“…Considering that certain patients harbouring ASPS present with metastasis, as also noted in the present series, additional treatment options such as pazopanib and immunotherapy are being increasingly considered for treating these otherwise dismal and chemorefractory tumours. 11,27,28,29 In the present study, palliative treatment was offered in cases with multiple metastases, including pazopanib in 3 cases.…”

“…[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.…”

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

“…Three‐dimensional alveolar structures are presented. A thin lining of endothelial cells is identified in a published report; however, we only see endothelial cells mixed with tumor cells in case 2. These cytological features are important to recognize to raise the possibility of ASPS.…”

Alveolar Soft Part Sarcoma located at the upper extremity: a case report and reviev of the literature

“…Fokal sahalarda CD10 pozitif reaksiyonu beklenmeyen bir durumdur, ancak Nabirajan A ve ark. (12) akciğerde metastatik ASPS olgusunda CD10 pozitifliği tanımlamış ve renal hücreli karsinom ile ayrımına dikkat çekmişler-dir. Olgumuzda, Pankeratin, EMA negatifliği ve ultrasonografik olarak renal kitle saptanmaması üzerine renal hücreli karsinom ekarte edildi.…”