ONCOCYTIC PAPILLARY RENAL CELL CARCINOMA (OPRCC): A CASE REPORT
Papillary renal cell carcinoma (PRCC) is the second most commonly encountered morphotype of renal cell carcinoma (RCC). PRCC is a malignant tumour derived from renal tubular epithelium: traditionally classified into type 1 and type 2 (1,2). Recently, an oncocytic variant of PRCC has been described (3). We describe a rare case of OPRCC recently underwent our observation.
Materials and Methods
83 years old caucasian man with incidental solid left renal mass, as showed from abdomen US and CT scan, underwent our observation wit LUTS without gross hematuria. Particular, CT scan showed a esophitic 47×36 mm upper pole vascularized renal mass. We performed a surgical enucleoresection with nephron sparing approach of the mass.
We have performed a lombotomic left antero-lateral approach to go to a neprhon sparing enucleoresection of the mass with hot ischemia by a selective closure of the upper pole arterial branch of the major renal artery. Total operating time has been 120 minutes with no significative blood loss. Not evidence disease at six months after surgery.
Specimen was fixed in 10% formalin buffer solution for 48 hours, then grossly sectioned and slices embedded in paraffin. Slides were stain with Hematoxylin/eosin. Immunohistochemistry was performed of the instrument Dako Omnis (Agilent Technologies, Santa Clara, US) with CD 10 (clone 56C6), Vimentin (clone V9), CD 177 (policlonal), Cytokeratin 7 (clone OV-TL12/30) and P504S/AMACR (clone 13H4) antibodies. Histologically, the tumor showed a papillary pattern; the papillary folds was formed by thin fibrovascular stalk, occasionally contain foamy macrophages, lined by single layer of epithelial cells with abundant granular eosinophilic cytoplasms and round nuclei, grade 2 sec. Vancouver classification. There were hemorrhagic spots and hemosiderothic histiocytes between papillae. No vascular invasion was seen. At periphery, the tumoral cells pushed a subtle fibrous capsula to perinephric fat without true invasion of adipose tissue. Tumoral cells were immunoreactive for CD 10, Vimentin and p504S/AMACR and negative for CD 177 and Cytokeratin 7.
Papillary renal cell carcinomas (PRCC) is a well-established subtype of RCC with characteristic gross and histological features and is further subdivided into 2 subtypes, type 1 and 2, for its distinct morphological feature and prognostic implications. Type 1 PRCC consist of small cells with low nuclear grade and a scant amount of cytoplasm arranged in a single layer, whereas type 2 PRCC tumor cells are larger, with abundant eosinophilic cytoplasm, higher nuclear grade, and nuclear pseudostratiﬁcation. The two types of PRCC also demonstrate different clinical behavior. Patients with type 2 have a poorer prognosis than those with type 1. Therefore, accurate subtyping of PRCC is important for prognosis and proper patient management. Recently, a new histopathologic variant of PRCC named oncocytic PRCC (OPRCC) has been described. It was first reported by Lefevre et al. in 2005 that 10 cases of RCC with the features of prominent papillary architecture, abundant granular eosinophilic cytoplasm and low-grade non overlapping nuclei (3-4).
The majority of patients OPRCC were identified by medical examination and the remaining presented with macroscopic hematuria or lumbar pain. Grossly, tumors were well demarcated and varied from 1.5 to 9 cm in diameter. Microscopically, typical OPRCC has fine papillary structures with delicate fibrovascular cores, lined with a single layer cell with large, deeply eosinophilic granular cytoplasm and round or polygonal-shaped nucleus exhibiting low nuclear grade in 10 cases (WHO/ISUP grade I-II). Most cases possessed hemosiderin-laden and foam-like cells. Focal necrosis presented. Immunohistochemically, the majority of tumors presented high expression rates of alpha-methylacylCoA racemase (AMACR), CD10 and vimentin, which were similar to type 2 PRCC. The immune markers including cytokeratin-7 (CK7), KSP-cadherin and EMA exhibited variable positive immunostaining. Genetically, FISH analysis demonstrated trisomy of chromosome 7 and trisomy of chromosome 17 in OPRCCs (5).
OPRCC is a PRCC variant with type 1 and type 2 histological patterns (1). Literature review shows only one case of disease related dead (3). A slow malignancy profile. It represents, otherwise, an important differential diagnosis element in urological clinical practice (2).
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3. Oncocytic papillary renal cell carcinoma: a clinicopathological study emphasizing distinct morphology, extended immunohistochemical profile and cytogenetic features. Xia QY1, Rao Q, Shen Q, Shi SS, Li L, Liu B, Zhang J, Wang YF, Shi QL, Wang JD, Ma HH, Lu ZF, Yu B, Zhang RS, Zhou XJ. Int J Clin Exp Pathol. 2013 Jun 15;6(7):1392-9.
4. Two Cases of Oncocytic Papillary Renal Cell Carcinoma. Matsuoka T, Ichikawa C, Fukunaga A, Yano T, Sugino Y, Okada T, Imai Y, Kawakita M. Hinyokika Kiyo. 2016 Apr;62(4):187-91. Japanese.
5. Oncocytic papillary renal cell carcinoma: A clinicopathological and genetic analysis and indolent clinical course in 14 cases. Han G, Yu W, Chu J, Liu Y, Jiang Y, Li Y, Zhang W. Pathol Res Pract. 2017 Jan;213(1):1-6. Epub 2016 Apr 28.