Baylor University Medical Center Proceedings April 2017 - 205

Primitive neuroectodermal tumors of the kidney
Geetha Narayanan, MD, DM, Varun Rajan, MD, and T. R. Preethi, MD

Ewing's sarcoma/primitive neuroectodermal tumor (ES ⁄ PNET) rarely occurs as a primary renal tumor. The disease affects young adults and
children and has an aggressive course. The clinical presentation and
imaging of these tumors are nonspecific, and they often present at an
advanced stage. We present the clinical features, imaging, diagnosis,
and treatment of 7 cases of renal PNET (4 men, 3 women; median age,
32 years). Common presenting symptoms were flank or abdominal pain
and a mass in the abdomen. On imaging, a large heterogenous infiltrating renal mass with areas of calcification, hemorrhage, and necrosis
and tumor thrombus can give a clue to the diagnosis of renal PNET.
Immunohistochemistry and molecular studies are essential to confirm
the diagnosis. The prognosis of renal ES ⁄ PNET is generally poor. Radical
nephrectomy combined with chemotherapy and radiotherapy is the standard treatment for renal PNET. An early and accurate diagnosis is crucial
for the proper management of these aggressive tumors.

wing's sarcoma/primitive neuroectodermal tumors
(ES ⁄ PNET) are a group of small round cell tumors primarily aﬀecting the bone and soft tissues. Very rarely,
they can occur as a primary renal tumor (1). The disease
commonly aﬀects young adults and children and runs an aggressive course (2). Molecular studies have established that ES
and PNET are part of the same tumor family and exhibit similar
biologic behavior. Most of the literature on renal PNET consists
of isolated case reports. The clinical presentation and imaging of
these tumors are nonspeciﬁc, and they often present at an advanced stage. We present the clinical features, imaging, diagnosis,
and treatment of 7 cases of renal PNET treated in our center.
METHODS
This is a retrospective analysis of 7 patients diagnosed with
PNET of the kidney treated in the Department of Medical
Oncology at Regional Cancer Center, Trivandrum, during a 15year period. The case records of the patients were studied with
respect to clinical presentation, diagnosis, treatment received,
and survival.
RESULTS
The details of the 7 cases are summarized in Table 1. In our
series, the median age was 32 years (range 16-73 years), and
Proc (Bayl Univ Med Cent) 2017;30(2):205-208

there were 4 women and 3 men. In all the patients except one,
the presenting symptom was abdominal pain and a huge mass
in the abdomen. In one case (#1), the renal mass was detected
during antenatal checkup when investigating fetal bradycardia.
Most of the patients presented at an advanced stage, and 4 out
of 7 had metastatic disease at presentation involving the lungs
and bone. Computed tomography (CT) imaging details were
available in 5 of our cases and showed heterogenous hypodense
mass lesions arising from the upper or lower poles of the kidney
with areas of hemorrhage and necrosis; 3 cases also had calciﬁcations. Histopathological examination showed a small round
blue cell neoplasm in all the cases, and immunohistochemistry,
which was available in 5 cases, was positive for CD99.
Only 3 of our cases had localized disease, and all underwent
radical nephrectomy; however, only 2 received adjuvant chemotherapy with vincristine, doxorubicin, cyclophosphamide/
ifosfamide, etoposide (VDE/IE), and one received adjuvant
irradiation to the primary site. Among our 4 cases with metastatic disease, 3 presented following radical nephrectomy, 3
received chemotherapy, and 3 were given palliative irradiation
to the metastatic site. Two patients did not receive any systemic
treatment after radical nephrectomy, and their follow-up details
were not known. Among the 5 patients who received chemotherapy, 4 were alive beyond 1 year, and one is alive in remission
at 15 months. The survival of our patient group ranged from
6 months to 18 months.
DISCUSSION
ES ⁄ PNET of the kidney was ﬁrst reported by Seemayer
and colleagues in 1975 (3) and is exceedingly rare. It usually
aﬀects young adults at a median age of 28 years and has a
male predominance of 3:1 (4, 5). In our series, the median age
was 32 years, and the male:female ratio was 4:3. The common
presenting symptoms are ﬂank or abdominal pain, mass in the
abdomen, and hematuria (6). Patients are usually asymptomatic
until the tumor reaches a large size; the maximum diameter of
From the Departments of Medical Oncology (Narayanan, Rajan) and Pathology
(Preethi), Regional Cancer Centre, Trivandrum, India.
Corresponding author: Geetha Narayanan, MD, DM, Professor and Head,
Department of Medical Oncology, Regional Cancer Centre, Trivandrum 695011,
Kerala, India (e-mail: geenarayanan@yahoo.com).
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