Interesting cases

Mixed neuroendocrine-non neuroendocrine tumor

A composite squamous cell carcinoma and neuroendocrine carcinoma of the kidney

The presence of a mixed neuroendocrine and non-neuroendocrine (MiNEN) tumor in the kidney is an extremely rare occurrence with only 20 cases reported worldwide. {1] We present a case of a composite squamous cell carcinoma and neuroendocrine carcinoma of the kidney.

Histopathological examination established a definitive diagnosis for our case. On gross examination, a right nephrectomy specimen measuring 17.0×12.0x6.0 cm with an attached ureter was seen. Serial slicing revealed a solid and cystic tumor which was replacing the whole renal parenchyma and measuring 15.0×11.0x4.0 cm. Histological examination showed a malignant neoplasm with two different morphologies. One comprising of epithelial squamous and the other comprising of a neuroendocrine component. The squamous part (Figure 2) showed tumor nests with prominent keratin pearls and with carcinoma in situ (Figure 1). The neuroendocrine part showed nests of monotonous cells. (Figure 3). The ureter and renal sinus were involved by the tumor. (Figure 1) Perinephric fat was free of tumor. The capsule was intact. Tumor staging was pT3. On immunohistochemistry, the epithelial component was positive for cytokeratin (Figure 5a) and p-63. The neuroendocrine component was positive for CD56 (Figure 5b) and focal cytokeratin and negative for synaptophysin and GATA-3.

According to the 2019 WHO classification, MiNEN neoplasms are defined as only those in which each component constitutes at least 30% of the tumor. [2]The type of neuroendocrine and non-neuroendocrine components of these tumors determine their behaviour. A primary neuroendocrine carcinoma (NEC) of the kidney is an extremely rare malignancy which includes both well-differentiated and poorly differentiated NECs. NEC may be associated with a non-neuroendocrine component in the kidney, termed a MiNEN of the kidney. So far, to the best of our knowledge, about 20 cases of MiNEN of the kidney have been reported in the literature. Most of these cases have small cell carcinoma and neuroendocrine tumor as the neuroendocrine (NE) component and either urothelial carcinoma or chromophobe renal cell carcinoma as the non-NE component. Most of these tumors arose either in the renal pelvis or the renal parenchyma and were associated with local invasion. The size of these tumors ranged from 3 cm to greater than 22cm. Hematuria and flank pain were the most common presenting complaints. The mean age of presentation was 61.7. [1]

1. La Rosa S, Sessa F, Uccella S. Mixed Neuroendocrine-Nonneuroendocrine Neoplasms (MiNENs): Unifying the Concept of a Heterogeneous Group of Neoplasms. Endocr Pathol. 2016;27(4):284-311. doi:10.1007/s12022-016-9432-9
2, 1. Pathology Outlines – Mixed neuroendocrine nonneuroendocrine neoplasm. Accessed November 7, 2023. https://www.pathologyoutlines.com/topic/colontumormxdnrndcrnnonnrndocrnnplsm.html

Name: Mahrukh Mumtaz
Institution: King Edward Medical University, Pakistan
Email: mahrukhmumtaz11@gmail.com
Twitter handle:@MahrukhMumtaz9

Name: Beenish Fatima
Institution: Chughtai Institute of Pathology, Pakistan
Email: beeniusman88@gmail.com

Name: Akhtar Sohail Chughtai
Institution: Chughtai Institute of Pathology, Pakistan
Email: dr.aschughtai@gmail.com

Kidney

MiNEN, kidney, composite tumor