PMC8287249_01
(A) Axial unenhanced CT image demonstrates a soft tissue mass (arrow) in the upper of the left ureter. On unenhanced CT scan, ureteral mass measures 37 HU. (B) Axial contrast enhanced CT in the arterial phase reveals heterogeneous enhancement of the lesions. On contrast enhanced CT scan, ureteral mass measures 55 HU. (C) Axial unenhanced CT image of 7 months after operation.
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The CT urogram revealed a soft tissue mass in the upper ureter approximately 1.5 cm from the left ureteropelvic junction ( Figure 1A ), which was slightly enhanced by contrast-enhanced CT ( Figure 1B ). No local recurrence or distant metastasis was found during the 14-month follow-up after the operation ( Figure 1C ).  Figure 4  depicts the clinical timeline of the patient.
Microscopic examination confirmed that the ureteral tumour cells were composed of two parts, and each component accounted for half of it (magnification, x100).
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Microscopic examination revealed that the tumour was composed of two types of tumour cells ( Figure 2 ).
Immunohistochemical staining of some tumour cells showed that (A) cluster of differentiation 56 (CD56; magnification, x400) was positive, but (B) chromogranin A (CgA; magnification, x100) and (C) synaptophysin (Syn; magnification, x100) were negative. Positive immunohistochemical staining for (D) cytokeratin 5/6 (CK5/6; magnification, x400) and (E) regulator protein 63 (P63; magnification, x400). (F) The Ki-67 (magnification, x100) index of neuroendocrine tumour cells was 90%, while that of squamous cell tumours was 40%. The black dotted lines show the boundary between neuroendocrine tumours and squamous carcinomas.
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The immunohistochemical results showed the tumour was positive for CD56 and negative for CgA and Syn ( Figure 3 ).
The clinical timeline of the patient.
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No local recurrence or distant metastasis was found during the 14-month follow-up after the operation ( Figure 1C ).  Figure 4  depicts the clinical timeline of the patient.