CASE REPORT

Primitive neuroectodermal tumor of the kidney confirmed byfluorescence in situ hybridization

SEIICHI KATO1, TOSHIMI TAKEUCHI1, TOMONARI ASANO1, YOSHIHITO BAN1,

TETSUYA YAMADA2, TADASHI HASEGAWA3 & NAOKI YAMAMOTO4

1Department of Urology and 2Central Laboratory, Gifu Municipal Hospital, Gifu-ken, Japan, 3Department of Surgical

Pathology, School of Medicine, Sapporo Medical University, Sapporo, Japan, and 4Department of Urology, Gifu University

Hospital, Gifu-ken, Japan

AbstractWe report a rare case of primitive neuroectodermal tumor of the kidney. The diagnosis was confirmed by theimmunohistochemical profile and fluorescence in situ hybridization in formalin-fixed, paraffin-embedded tissues. Thepatient received intensive chemoradiotherapy after radical surgery and remains alive without recurrence 1 year after initialpresentation.

Key Words: Primitive neuroectodermal tumor, kidney

Introduction

We present a rare case of renal primitive neuroecto-

dermal tumor (PNET) which occurred in an adult.

The diagnosis was confirmed by the detection of a

Ewing’s sarcoma (EWS) rearrangement. The patient

received intensive chemoradiotherapy after radical

surgery and remains alive without recurrence 1 year

after initial presentation.

Case report

A 33-year-old female with no significant previous

medical history presented with right flank pain and

fever. Physical examination and routine laboratory

data were unremarkable. CT revealed a 8.0�/

8.0 cm2 mass in the inferior portion of the right

kidney. The mass exhibited an homogeneous mini-

mal enhancement with slightly higher attenuation

than the skeletal muscle (Figure 1). The patient

underwent a right radical nephrectomy. A periopera-

tive examination showed that there was no involve-

ment between the tumor and neighboring organs or

the renal vein.

Histological examination showed the tumor to

be composed of small cells with uniform round

nuclei and minimal cytoplasm forming many

Homer�Wright pseudorosettes (Figure 2A). Immu-

nohistochemically, the tumor exhibited expression of

vimentin, neuron-specific enolase and CD99 but no

expression of desmin, alpha-smooth muscle actin,

Correspondence: Naoki Yamamoto, MD, Department of Urology, Gifu University Hospital, 1-1 Yanaido-Gifu-shi, Gifu-ken 501-1194, Japan. Fax: �/58 230

6339. E-mail: yamanao@cc.gifu-u.ac.jp

Figure 1. A CT scan revealed a solid tumor in the lower pole of

the right kidney. The tumor was slightly enhanced.

Scandinavian Journal of Urology and Nephrology, 2007; 41: 75�76

(Received 7 March 2006; accepted 28 April 2006)

ISSN 0036-5599 print/ISSN 1651-2065 online # 2007 Taylor & Francis

DOI: 10.1080/00365590601135832

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muscle-specific actin, pan-cytokeratin, epithelial

membrane antigen, S-100, CD34 or KIT/CD117

(Figure 2B). Interphase fluorescence in situ hybri-

dization (FISH) on routinely formalin-fixed, paraf-

fin-embedded tissues using a commercially available

EWSR1 (22q12) dual-color, break-apart rearrange-

ment probe indicated the presence of t(11;22),

confirming the diagnosis of PNET (Figure 2C).

The patient received irradiation to the renal bed in

conjunction with chemotherapy (cisplatinum and

etoposide). The patient remains alive without evi-

dence of recurrence 1 year after initial presentation.

Discussion

EWS/PNET usually occurs in soft tissues but

occasionally arises within visceral organs. Recently,

EWS and PNET have been considered to be the

same disease entity according to the WHO classifi-

cation.

EWS/PNET often shows a morphologic overlap

with other small, blue, round-cell tumors, therefore

necessitating immunohistochemical analyses. In

some cases these may be difficult to interpret,

although expression of CD99 has been helpful in

confirming the diagnosis of EWS/PNET [1].

EWS/PNET is characterized by non-random

chromosomal translocations involving the EWS

gene. The translocation t(11;22)(q24;q12) is the

commonest and leads to formation of the EWS�FLI1 fusion protein. In�/90% of cases, EWS/

PNET has the t(11;22) chromosomal rearrange-

ment. Dual-color, break-apart interphase FISH

assays provide a highly specific and sensitive method

for identifying chromosome 22 rearrangements that

can definitively establish the diagnosis of PNET/

EWS. We could detect this rearrangement by means

of FISH using formalin-fixed, paraffin-embedded

tissues. These translocations are detectable not only

in this way but also with reverse transcriptase-

polymerase chain reaction (RT-PCR). However,

RT-PCR is less sensitive in formalin-fixed, paraffin-

embedded tissue than in frozen tissue. When only

paraffin blocks are available, FISH is the method of

choice [2].

Renal PNET is more aggressive than when PNET

occurs at other sites. The optimal therapeutic

management is unclear, but in general the tumor is

best treated with surgery followed by radiotherapy

and chemotherapy. The chemotherapeutic regimen

warrants continuing development and consideration

for use in future trials [1].

References

[1] Ruszat R, Casella R, Bachmann A, Gasser TC, Sulser T.

Primitive neuroectodermal tumor of the kidney with hyaline

cells. Urol Int 2005;/75:/184�6.

[2] Surace C, Storlazzi CT, Engellau J, Domanski HA, Gustafson

P, Panagopoulos I, et al. Molecular cytogenetic characteriza-

tion of an ins(4;X) occurring as the sole abnormality in an

aggressive, poorly differentiated soft tissue sarcoma. Virchows

Arch 2005;/447:/869�74.

Figure 2. (A) The tumor was composed of small cells with uniform round nuclei and minimal cytoplasm forming many Homer�Wright

pseudorosettes. (B) The tumor cells showed diffuse and strong membranous staining for CD99. (C) The tumor cells showed one fused, one

orange and one green signal pattern (arrows) , indicating a rearrangement in one copy of the EWSR1 region.

76 S. Kato et al.

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