Case of the Week

Week 14: Case 1: Uropathology: Metastatic papillary renal cell carcinoma presenting with peritoneal carcinomatosis

November 16, 2017

Prepared by: Andrea Lightle (Fellow) and Hongying Huang (Attending).

History:

The patient is a 50 year-old female, with a past medical history significant only for kidney stones. Work-up for kidney stones revealed a large mass in the left kidney with thrombus of the inferior vena cava, enlarged perinephric, peri-caval, and para-aortic lymph nodes, and scattered lung nodules. An exploratory laparotomy was performed, in which the surgeon noted the renal mass encasing the aorta and left common iliac artery, diffuse peritoneal carcinomatosis, and metastatic disease in the left salpinx. Biopsies from the peritoneum and left salpinx were submitted for diagnosis


Figure1: Metastatic carcinoma located within the mucosal folds of the fallopian tube. The overlying epithelium is benign. (H&E, 100x)


Figure 2: The peritoneal biopsy shows metastatic carcinoma with a focal micropapillary architecture and microcalcification. The tumor cells have large nuclei with prominent nucleoli (H&E, 200x)

Immunohistochemistry

CK7

Positive

CK5/6

Positive

34βE12

Positive

PAX8

Positive

p53

Patchy

CK20

Focal

PR

Focal, weak

INI1

Positive

WT1

Negative

GATA3

Negative

ER

Negative

p63

Negative

Ki67

20%

Click for Diagnosis

Metastatic papillary renal cell carcinoma

Click for Discussion

Papillary renal cell carcinoma is the second most common subtype of RCC, accounting for 15% of cases. It is characterized by papillary architecture, but can also display tubular and solid patterns. The papillae consist of fibrovascular cores lined by a single layer of amphophilic cuboidal cells (type 1), a pseudostratified layer of more deeply eosinophilic columnar cells (type 2), or a single layer of oncocytic cells with low-grade nuclei linearly arranged toward the cell apices (oncocytic type). Foamy macrophages are frequently seen within the fibrovascular cores. As in all renal epithelial tumors, PAX8 is positive, whereas CK7 is more often positive in type 1 rather than in type 2 tumors. The prognosis for papillary RCC is overall better than for clear cell RCC. While the most common sites for metastatic renal cell carcinoma are the lung, liver, and bones, peritoneal metastasis has been reported, and in one series was more frequent in metastatic papillary RCC than in metastatic clear cell RCC1.

Click for References

1. Tirumani, S.H., Souza, D., Krajewski, K.M. et al. Abdom Radiol (2016) 41: 295. https://doi-org.ezproxy.med.nyu.edu/10.1007/s00261-015-0569-7

Week 14: Case 2: Uropathology: Malakoplakia clinically simulating renal cell carcinoma

November 16, 2017

Prepared by: Andrea Lightle (Fellow) and Fang-Ming Deng (Attending).

History:

The patient is a 60-year-old female with end-stage kidney disease due to diabetes mellitus, status post renal transplant one year prior. She has been followed by urology since her transplant for recurrent E. coli UTI’s. A CT scan for kidney stones performed 4 months prior noted a hyperdense 2.0 cm lesion in the upper pole of her left native kidney. An MRI demonstrated internal enhancement in the lesion, compatible with a neoplasm. A laparoscopic nephrectomy was performed. Gross examination revealed an atrophic kidney with three tan-yellow well circumscribed lesions in the renal medulla, measuring 1.2 cm, 0.6 cm, and 0.3 cm.


Figure 1: The renal parenchyma is replaced by an inflammatory reaction characterized by predominance of eosinophilic histiocytes (H&E, 200x)


Figure 2: Histiocytes contain scattered basophilic, targetoid, cytoplasmic inclusions or bodies (H&E 400x)

Click for Diagnosis

Malakoplakia

Click for Discussion

Malakoplakia is an uncommon inflammatory disorder which occurs most commonly in the urinary tract, but has also been reported in the prostate, testis, vagina, GI tract, lung, bone, brain, and skin. It is more common in females (ratio 4:1) and is more frequently seen in immunocompromised patients. Renal involvement frequently simulates RCC clinically and radiologically.

Malakoplakia is associated with defective intracellular digestion of ingested microorganisms, typically Gram-negative bacteria, by macrophages. Pathognomonic targetoid intracellular inclusions known as Michaelis-Gutmann bodies form when calcium and iron are deposited on the accumulated bacterial glycolipids within phagolysosomes.

Grossly, the lesions can be diffuse, segmental, or focal, with irregular poorly-defined yellow masses centered within the renal medulla. Microscopically the renal parenchyma is replaced by an inflammatory infiltrate containing predominantly PAS+ histiocytes with eosinophilic cytoplasm (von Hansemann histiocytes). These contain scattered Michaelis-Gutmann bodies which can be visualized with PAS, calcium, and iron stains.

The differential diagnosis for malakoplakia includes xanthogranulomatous pyelonephritis, which is characterized by foamy histiocytes and the absence of Michaelis-Gutmann bodies.

 

Click for References

1. Esparza, A. R., McKay, D. B., Cronan, J. J., & Chazan, J. A. (1989). Renal parenchymal malakoplakia: histologic spectrum and its relationship to megalocytic interstitial nephritis and xanthogranulomatous pyelonephritis. The American journal of surgical pathology, 13(3), 225-236.

2. McClure, J. (1983). Malakoplakia. The Journal of pathology, 140(4), 275-330.

3. Purnell, S. D. K., Davis, B., Burch-Smith, R., & Coleman, P. (2015). Renal malakoplakia mimicking a malignant renal carcinoma: a patient case with literature review. BMJ case reports, 2015, bcr2014208652.