The 2016 World Health Organization Classification of Tumors recognized mucinous tubular and spindle cell carcinoma (MTSCC) as a rare histological variant of renal cell carcinoma (RCC). To date, a limited number of studies have reported this tumor concerning histology, and only a handful of those have reported cytological and ultrastructural features. This study aims to report a case of MTSCC in a female patient in her early 50s who presented with a chief complaint of gross hematuria, and to discuss relevant cytological and ultrastructural findings. Imaging revealed a 30 mm tumor in the left kidney, suggesting the presence of RCC, and left nephrectomy was performed. In addition, scratched cytology of tumor surface revealed clusters of tumor cells with clear cell boundaries extending two-dimensionally in papillary or dendritic arrangements with interspersed blood vessels and stromal components that were stained light green. Histologically, the tumor was composed of small and uniform cells arranged in elongated tubular architectures and spindle fascicles with occasional papillary structures; the stroma was acidophilic and contained colloidal substances that tested positive for Alcian blue and periodic acid-Schiff stain. Concordant with immunohistochemical results, the tumor was diagnosed with MTSCC. Furthermore, transmission electron microscopy revealed tubular structures with microvilli, abundance of mitochondria in the cytoplasm, cellular interdigitations and widened interstitium.
Read full abstract