Papillary renal cell carcinoma within a renal oncocytoma: Case report of very rare coexistence

Case report of a combined oncocytoma and type 1 papillary renal cell carcinoma: a rare entity

An extremely rare renal hybrid tumor composed of papillary renal cell carcinoma (PRCC) and renal oncocytoma (RO) within the same tumor is described. Only eight previous cases are documented in the literature. A 44-year-old man showed a 3.5 cm renal mass composed by areas with tubulo-papillary structures made up with small cells with scanty cytoplasm adjacent to polygonal cells forming solid sheet and tubules with abundant eosinophilic cytoplasm and uniform, round central nuclei without mitoses. Complete immunohistochemical panel suggested a diagnosis of type 1 PRCC combined with RO. Contrary to previous cases of hybrid renal tumors reported in the literature, no pseudocapsule divided the two histotypes of tumors. Our patient is the youngest among the previous reports being 44. Collision tumours have previously been described, although mixed renal tumours composed of oncocytoma and PRCC is extremely rare. There is no evidence to suggest a relationship between oncocytoma and papillary RCC since they originate from different cells and have different prognoses. Given the possibility of oncocytomas to harbour other tumours, we suggest careful examination of the samples to exclude the presence of an associated malignant neoplasm, which might have a significantly worse prognosis than oncocytoma. Differential diagnosis is needed, and immunohistochemical stains are of great help in distinguishing between the two histological components.

A back-to-back tumor composed of papillary renal cell carcinoma and oncocytoma treated by laparoscopic partial nephrectomy: a case report

Background

Renal oncocytoma is the most common benign renal tumor, and papillary renal cell carcinoma is the second most common histologic subtype of renal cell carcinoma. Renal tumors containing different components such as papillary renal cell carcinoma and oncocytoma are extremely rare.

Case presentation

A renal mass was incidentally detected in a 52-year-old Korean woman, and a computed tomographic scan showed a 32-mm multicystic mass with some calcifications in the lower pole of the right kidney. She underwent laparoscopic partial nephrectomy without any perioperative complications. We found a papillary renal cell carcinoma and an oncocytoma in a tumor mass.

Conclusions

The possibility of a mixed malignant tumor should be considered while treating benign tumors such as oncocytoma.

Primary collision tumors of the kidney composed of oncocytoma and papillary renal cell carcinoma: A review

BACKGROUND

There are well known cases of hybrid tumors of chromophobe renal cell carcinoma (RCC) and oncocytoma in kidney, where both tumors have the same cell of origin - intercalated cell of the collecting duct. However, collision tumors composed of neoplasms originating from different cell lineages such as oncocytoma and papillary RCC are extremely rare. Herein, we made a collective literature review of reported cases of collision tumors composed of oncocytoma and papillary RCC, adding a case that we recently experienced.

MATERIAL AND METHODS

A PubMed database was search for collision tumors of the kidney composed of oncocytoma and papillary RCC and a collective literature review was made. To this cohort, we also added a recently encountered case with similar, confirmed by immunohistochemistry, morphological features.

RESULTS

To date 8 cases of a collision tumor composed of papillary RCC and oncocytoma have been described in the literature. All of them had a smaller papillary RCC component present within a larger oncocytoma.

CONCLUSION

Because of a few cases of such a collision tumors reported, it is difficult to make classification and right clinical management of these patients. None of the reported cases had tumor recurrence or progression on a follow-up. The presence of only small portion of papillary RCC in a large oncocytoma raises a possibility of under-sampling of malignant component in large oncocytomas in core biopsy or surgically resected specimens. We recommend better sampling, particularly at the periphery of otherwise classic oncocytomas to unveil this possible association.

Primary collision renal tumor of papillary renal cell carcinoma within an oncocytoma: emergency presentation of a rare entity

BACKGROUND

The coexistence of an oncocytoma and a papillary renal cell carcinoma (PRCC) in the same neoplastic mass constitute a collision tumor and is an extremely rare entity. Until now, only six incidentally diagnosed cases have been reported, concerning patients older than 65 years.

CASE REPORT

A 57-year-old man was admitted to the Emergency Department with acute pain and anemia, due to renal hematoma following rupture of such a neoplastic collision mass. The patient underwent an emergency nephrectomy, which revealed a 10.6 cm oncocytoma and a 1.3 cm PRCC. He had an uncomplicated postoperative recovery and remained healthy at the 65-month follow-up, the longest of all previous cases.

CONCLUSION

While prognosis appears favorable, the current report shows that these collision tumors may cause emergency and dangerous medical conditions that deserve prompt treatment. HIPPOKRATIA 2017, 21(2): 105-107.