Pseudoangiosarcomatous squamous cell carcinoma: a rare subtype of squamous cell carcinoma that needs to be differentiated from angiosarcoma and has a poor prognosis.

This study aimed to investigate the formation mechanism of  Pseudoangiosarcoma squamous cell carcinoma (PASCC). The researchers reviewed ten cases of PASCC and summarize their clinical outcomes, pathological morphological traits, immunophenotypes, treatment plans and the corresponding follow-up data. Results showed that the pathological morphology revealed complex reticular structures, where numerous tracts of anastomose, and lacunar structures lined with atypical neoplastic cells, which resembles the histopathological appearance of angiosarcoma. Particularly, we observed pathologic patterns that resemble Sclerosing Epithelioid Fibrosarcoma (or Myxoid Fibrosarcoma) in the patients who suffered a relapse. All cases present negative results for vascular markers (CD31, ERG) and positive results for epithelial markers (CK-pan, p40). The average age of the participants is 60 years old (range: 48-79), relative aged, and there is no significant difference between male and female participants (6 men and 4 women). The locations of neoplasms involve face (n=3), upper limbs (n=1), waist(n=1), cervix uteri (n=1), lungs (n=2), thyroid (n=1), and breasts (n=1). All participants had received clinical follow-ups that range from 4 to 47 months, during which the researchers observed Lymph Node Metastases developed in three participants (out of 10; 30%); Distant Metastases in five participants (out of 10; 50%); two local recurrences at the site of surgical resection; and four deaths due to disease (out of 10; 40%), with 9.5 months estimated median survival time and 9 months mean survival time. It was concluded that PASCC presents the tendency for recurrence and metastasis. Accurate pathological diagnosis and standardized medical procedures are crucial to the treatment of PASCC. Epithelial-Mesenchymal Transformation (EMT) and P53 gene mutation are involved in the formation of PASCC.