Multilocular cystic renal cell carcinoma: clinicopathological and immunohistochemical characters

ABSTRACT

Multilocular cystic renal cell carcinoma [MCRCC] is a rare and distinct subtype of renal cell carcinoma [RCC]. It is characterized by unique gross and microscopic features. As well as the outcome of this tumor is excellent in comparison to the conventional type of RCC. Additionally, there is no evidence of progression or recurrence is seen after surgery among MCRCC, differing from conventional RCC. The aim of this work is to evaluate the clinicopathological features of this tumor. Also, to study their immunohistochemical characters comparing with conventional RCC. As well as try to see the differential diagnosis between MCRCC and other renal cystic lesions in particular RCC with cystic areas, cystic nephroma, and multilocular renal cysts. This work was performed on 20 cases of different renal tumors. These cases were collected retrospectively from the surgical pathology files at Department of Pathology, King AbdulAziz University Hospital, Jeddah through the period 2000 to 2007. The clinicopathological parameters including gross and microscopic features were studied. Then panel of immunohistochemical markers including epithelial membrane antigen [EMA], cytokeratin pan [CK-pan], renal cell carcinoma marker [RCC], CD10, vimentin, and cytokeratin 7 [CK7] were preformed. Other additional markers were added when needed. According to the criteria of the World Health Organization [WHO] 2004, the properly selected cases with full criteria of MCRCC were detected in 4 cases [20%]. The remaining of the studied cases were 13 cases [65%] conventional type RCC, one case [5%] renal leiomyosarcoma, one case [5%] sarcomatoid RCC and one case [5%] was clear cell renal cell sarcoma. The age of all cases was ranged from 2 years to 60 years [the mean was 50 years]. The gender of the included cases was 14 cases [70%] male and 6 cases [30%] were female. Yet, the gender of the included MCRCC cases in our study was 3 cases [75%] male and one case [25%] was female. Their ages were ranged from 30 years to 60 years. 3 cases [75%] of MCRCC were Fuhrman grade 1 and one case was Fuhrman grade2. As well as 3 cases of them were suffered from loin pain and in one case the tumor was discovered incidentally during routine abdominal ultrasound check-up. All cases were undergone for nephrectomy. Histologically there were variable sized cysts lined by single layer of neoplastic cells. The tumor stage in all cases of MCRCC was 1. So, MCRCC has a lower pathologic nuclear grade and stage. Immunohistochemically MCRCC cases were immunoreactive for EMA, RCC marker, vimentin, and CK7. Yet, MCRCC cases showed lowered immunoreactivity for CD10, and all eases were lacked cytokeratin 20 [CK20]. MCRCC represents a distinct subtype of RCC. The prognosis of MCRCC is excellent in comparison to other types of RCC. Most of MCRCC cases were Fuhrman grade 1, and stage 1. Some cases of MCRCC can be seen incidentally during investigation for unrelated conditions. The diagnosis of MCRCC is strictly related to its unique gross and microscopic features. As well as this tumor must be differentiated from other cystic renal lesions. Immunohistochemically these tumors were immunoreactive for the same markers of conventional RCC. Yet, CD10 showed lowered percentage of positive immunoreactivity, and CK7 showed strong positivity in comparison to conventional RCC