Table 1 Characteristics of MTSCC cases with sarcomatoid change (Dhillon et al. 2009; Pillay et al. 2008; Simon et al. 2008; Isono et al. 2020; Arafah and Zaidi 2013; Sugimoto et al. 2019; Kenney et al. 2015; Gong et al. 2020)

Our

Case

23/M

bilateral flank pain and fever

well-defined heterogeneously relatively hypo-enhancing, ball-shaped, renal mass on CT scan.

Well circumscribed mass with necrosis on cut surface.

Tubular and spindle cell areas in a mucinous stroma and sarcomatoid change in 70% of tumor.

CK7: Positive

AMACR:Positive.

PAX-8: Focal positive.

CA-IX: Focal positive.

CD10: Focal weak positive.

Radical nephrectomy.

Pulmonary and liver lesions on CT scan suspicious for metastases. Lymph node metasis confirmed on histology.

Alive on six-month follow-up.

1

71/F

Back Pain

8 cm heterogenous mass on CT scan

Poorly circumscribed tumor with hetrogenous tan yellow and white cut surface and necrotic areas.

Tubular and spindle cell morphology with sarcomatoid change in 60% of tumor

Tumor showed positivity for CK7,Vimentin,Epithelial membrane antigen and CAM5.2

Radical nephrectomy.

Expansile lytic lesions in bilateral ribs, L4 vertebral body and multiple bilateral lung nodules on CT scan.

The patient died 9 months after the

nephrectomy.

2

72/F

Flank Pain, hematuria

Not Available

well-circumscribed tumor in the upper pole measuring 7 × 7 × 5 cm with yellowish cut surface showing necrosis and hemorrhage.

cords and tubules lined by cuboidal cells with abrupt transition to spindle cell areas set in a mucinous stroma. Multiple foci of atypical spindle cells.

CK AE1/

AE3 and CK7 positive while AMACR focal weak positive.

Radical nephrectomy.

Adrenal gland and lymph nodes metastasis were not present.

Alive and in a good state of health after 12 months of follow-up.

3

64/F

Back Pain with lower extremity weakness

MRI revealed a left kidney mass which was extending to retroperitoneum and was compressing the spinal cord.

Left kidney tumor with a tan yellow necrotic cut surface.

Bland tubular and spindle cell component in a mucinous stroma with sarcomatoid degeneration in 40% of viable tumor.

Tumor was positive for pancytokeratin, vimentin, CD10, CK7, CK18, CK19, epithelial membrane antigen, and AMACR

Radiotherapy followed by tumor embolization and radical nephrectomy with vertebral body resection.

Thoracic vertebral bodies, liver, malignant pleural effusion and adrenal gland metastasis

Patient expired 3 weeks after surgery.

4

80/M

Discomfort and a palpable 3-cm mass in the right collarbone

CT revealed expansive lesions that in-

volved the inferior pole of the left kidney.

A 3.0 × 3.0 × 2.5-cm, poorly-circumscribed tumor with greyish-white and focally tan colored cut-surface.

Tubules lined by bland cuboidal cells mixed with spindle cells with extracellular mucinous and sarcomatoid component.

CD10, AMACR, CK7, EMA, E-cadherin, ZE-

B1, Slug, TWIST, and vimentin were positive.

Partial nephrectomy

peritonitis carcinomatosa and multiple metastases.

Patient died 7 months after surgery.

5

43/M

Incidental finding

MRI showed a tumor with cystic degeneration measuring 50mm.

Tumor consisted of heterogenous yellowish nodular cut-surface with hemorrhage.

Admixture of bland tubular and spindle cells mixed with atypical spindle cells in a mucinous stroma.

Positive for AMACR and PAX8. CK7, CD10 were negative.

radical nephrectomy with lymph

nodes resection followed by tyrosine kinase inhibitor, sunitinib and axitinib.

lymph node metastases and peritoneal dissemination.

Patient died due to the disseminated disease

12 months after the surgery

6

64/M

Pain abdomin, altered bowel habits, and

swelling on the left side of the

abdomen.

CT scan showed

a 20 cm kidney mass with cystic and solid components.

A circumscribed mass with tan-yellow cut-surface and areas of hemorrhage and necrosis.

Bland tubular and spindle cell component in a mucinous stroma with sarcomatoid degeneration in 20% of viable tumor.

AMACR and CK7 were strong diffuse positive, while epithelial membrane antigen was focally positive

Radical nephrectomy

Liver, spleen and left pleural metastasis.

Patient died after 8 months of surgery due to multiple metastasis.

7

80/M

Known case of chronic obstructive lung disease.

11 cm left kidney tumor.

Discrete pseudocapsule with focal infiltrative borders and extensive necrosis(70%)

Mucin poor MTSCC with high grade spindle cell sarcoma component comprising of 20% of tumor.

CK7, AMACR strong Positive in both tubular and spindle cell areas.

Radical nephrectomy.

No radiological evidence of metastasis.

Patient had disease free survival on 4 months of follow-up