Indian Journal of Pathology and Microbiology

CASE REPORT
Year
: 2017  |  Volume : 60  |  Issue : 4  |  Page : 574--576

Renal cell carcinoma with t(6,11): A case report and review of literature


KS Jansi Prema1, KS Devanathan2, Anila Abraham Kurien1,  
1 Department of Pathology, Center for Renal and Urological Pathology, Chennai, Tamil Nadu, India
2 Department of Urology, Sree Paduka Speciality Hospital, Tiruchirappalli, Tamil Nadu, India

Correspondence Address:
Dr. K S Jansi Prema
Renopath lab, No 27 and 28, VMT nagar, Kolathur, Chennai - 600 099, Tamil Nadu
India

Abstract

Renal cell carcinomas (RCCs) with t(6,11) are very rare tumours. Only a few cases have been reported so far. t(6,11) results in fusion of alpha gene and transcription factor EB (TFEB) gene resulting in the overexpression of TFEB. The specific light and immunohistochemical features help in the diagnosis of this rare type of tumor. We report a case of t(6,11) RCC in a 38-year-old female who was incidentally found to have a right renal mass. We present this case to emphasize the typical light microscopic picture of this extremely rare tumor. Two population of cells are seen: larger cells with abundant cytoplasm and smaller cells with scant cytoplasm. Smaller cells are arranged around hyaline nodules resulting in the formation of characteristic pseudorosettes. Immunohistochemically, these tumors are diffusely positive for vimentin and focally positive for HMB 45 and CD 117. Knowledge about the typical biphasic light microscopic appearance and the characteristic immunohistochemical features help in the diagnosis of this rare type of translocation associated RCC.



How to cite this article:
Jansi Prema K S, Devanathan K S, Kurien AA. Renal cell carcinoma with t(6,11): A case report and review of literature.Indian J Pathol Microbiol 2017;60:574-576


How to cite this URL:
Jansi Prema K S, Devanathan K S, Kurien AA. Renal cell carcinoma with t(6,11): A case report and review of literature. Indian J Pathol Microbiol [serial online] 2017 [cited 2021 Apr 18 ];60:574-576
Available from: https://www.ijpmonline.org/text.asp?2017/60/4/574/222990


Full Text



 Introduction



Renal cell carcinomas (RCCs) with t(6,11) are very rare tumours. Only about 50 cases have been reported so far. It was first described in 2001 by Dr. Argani et al.[1] and was recognized by the International Society of Urological Pathology Vancouver Classification of Renal Neoplasia in 2013[2] and by the WHO in 2016. The specific light microscopic and immunohistochemical features help in the diagnosis of this rare type of tumor. t(6,11) results in the fusion of alpha gene and transcription factor EB (TFEB) gene resulting in the overexpression of TFEB.[3],[4]

 Case Report



This patient is a 38-year-old female who was found to have a right renal mass while being evaluated for irregular menstrual cycles. Contrast-enhanced computed tomography showed contrast enhancing right renal mass [Figure 1]a. Laparoscopic right radical nephrectomy was performed. There was a well-circumscribed tumor measuring 4.8 cm in the middle pole of the kidney which was firm, nodular, and gritty to cut [Figure 1]b. Focal hard areas were also present. Corticomedullary junction was not preserved. Grossly perinephric fat was not involved.{Figure 1}

Light microscopy showed a well-circumscribed neoplasm consisting of two populations of cells: large and small cells [Figure 2]a. The large cells were arranged in sheets. They were polygonal with abundant clear-to-granular eosinophilic cytoplasm with small round nucleus and visible nucleoli. The smaller cells were arranged in an alveolar pattern around hyaline nodules forming pseudorosettes [Figure 2]b. They had scant cytoplasm and small round nucleus with dense chromatin. Large sheets of hyaline, areas of calcification and ossification were seen between the tumor cells. Psammoma bodies were also seen focally. Mitosis was not present in both the population of cells. Dark brown pigment granules were seen in the cytoplasm of tumor cells. Perl's stain for iron was negative. Immunohistochemistry showed diffuse positivity for vimentin and focal positivity for HMB 45 and CD 117 in the tumor cells [Figure 2]c,[Figure 2]d,[Figure 2]e. A diagnosis of RCC with t(6,11) was made based on the characteristic light microscopic features and immunohistochemical studies.{Figure 2}

 Discussion



The WHO has classified t(6,11) RCC under the MiT family (microphthalmia transcription factor) of translocation RCC. MiT family of transcription factors includes TFE3, TFEB, TFEC, and MITF. t(6,11)(p21; q12) leads to fusion of alpha gene on 11q12 or q13 with another gene called TFEB on chromosome 6p21 causing TFEB protein overexpression.[3],[4] Alpha gene is an untranslated gene and its function is not known so far. Gene fusions involving TFE3 occur in Xp11 translocation RCC. The WHO has recognized Xp11 translocation RCC in the year 2004. Both Xp11 translocation RCC and t(6,11) RCC have many common features; hence, these two types have been classified under the MiT family translocation RCC.

t(6,11) RCC most commonly involves children and young adults, unlike clear cell RCC. Only rarely are older adults affected. The mean age of presentation is in the fourth decade, though age range of 3–68 years has been reported, with equal frequency in both sexes. The initial presentation includes fever, abdominal pain or right hypochondriac mass. It may be found incidentally as in our case.

Microscopically, two population of cells are seen: large cells with abundant cytoplasm and smaller cells typically arranged around the hyaline material. Melanin pigment may also be present in the cytoplasm.[5]

Unlike other RCCs, t(6,11) RCC under express epithelial markers such as epithelial membrane antigen and cytokeratin. At least focally, t(6,11) RCC is positive for CD10 (RCC marker) and Cam 5.2(low molecular weight cytokeratin). They more often express cathepsin K, HMB45 and Melan A.[6] Melan A is diffusely positive and HMB 45 is only focally positive. Our case also showed focal positivity for HMB45. But t(6,11) RCC, unlike melanoma, do not label for MiTF and S 100. PAX8 is a transcription factor for renal tubular epithelium, and these tumors are positive for PAX8. PAX8 positivity helps to distinguish t(6,11) RCC from epitheloid angiomyolipoma, which is also positive for melan A and HMB 45. Immunohistochemistry for antibodies to TFE3 was negative in all the cases performed so far, thus differentiating it from Xp11 translocation RCC. In t(6,11) RCC, CD117 positivity is more frequent than in Xp11 translocation RCC. In Xp11 translocation RCC, vimentin is either negative or only focally positive, whereas in t(6,11) RCC, vimentin is diffusely positive.[7],[8] Our case showed diffuse positivity for vimentin and focal positivity for CD117.

In some patients, t(6,11) RCC has occurred following cytotoxic chemotherapy for other unrelated conditions. No such history was present in our patient. They are generally considered as indolent neoplasms, though recurrence has been reported in 17% of the patients.[9] In one patient, metastasis to the ribs occurred 8 years after the initial diagnosis.[10] This underscores the importance of long-term follow-up. Our patient did not have any evidence of metastasis by imaging studies. She is currently on regular follow-up.

Knowledge about the typical biphasic light microscopic appearance and the characteristic immunohistochemical features helps in the diagnosis of this rare type of translocation associated RCC.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

References

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