germ cell tumors often complicate uncorrected cryptorchidism with an incidence of 9.8% reported by martin .
occurrence of pure yolk sac tumor however is uncommon in the undescended testis with only a few cases reported in literature .
we present a case of yolk sac tumor in a 2-year - old boy in the undescended testis which was primarily diagnosed by fine needle aspiration cytology ( fnac ) .
a 2-year - old boy presented to the pediatric surgical out patient department ( opd ) with 5 days history of a right sided abdominal mass . on examination the lump was 5 cm  5 cm in size , firm in consistency with restricted mobility .
a tumor was noticed at the right renal hilum , causing ureteric narrowing with resultant hydronephrosis along with presence of multiple , large oval , heteroechoic lesions in the right iliac region and reteroperitoneum .
possibility of lymphoma was suggested . due to the absent testis in the right scrotum , testicular neoplasm
smears were highly cellular showing tumor cells in variably sized loose clusters with occasional cells forming glomeruloid structures [ figure 1 ] .
the nuclei were round to oval with irregular nuclear membranes , coarsely clumped chromatin and 0 - 1 nucleoli .
there was abundant mucoid material in the background with presence of intracytoplasmic as well as extracellular periodic acid - schiff ( pas ) positive hyaline globules .
this was corraborated by the raised alpha feto - protein ( afp ) levels ( > 2000
beta human chorionic gonadotropin ( hcg ) levels were within normal limits ( 1.61 miu / ml ) .
contrast - enhanced computed tomography ( cect ) of the chest and abdomen were performed and revealed an elongated nearly oval shaped heterogeneously enhancing lesion in the right lower abdomen .
multiple heterogeneously enhancing retroperitoneal lymph nodes , right sided hydroureteronephrosis with left sided pleural deposits was also seen . in view of undescended testis , possibility of germ cell malignancy was suggested .
it was gray to yellow in colour with some myxoid areas . also present in the specimen
sections were taken extensively and showed features consistent with yolk sac tumor with cells arranged in microcystic - reticular , myxomatous and focal macrocystic , alveolar - glandular and papillary patterns [ figure 2 ] .
the rete testis , epididymis and surgically resected end of the spermatic cord were free of tumor .
intracytoplasmic and extracellular hyaline globules present in the tumor were pas positive and diastase resistant .
cd30 , epithelial membrane antigen ( ema ) and carcinoembryonic antigen ( cea ) were negative ruling out embryonal carcinoma and choriocarcinoma .
smear showing clusters of pleomorphic cells with abundant mucoid material in the background ( giemsa stain , 400 ) .
inset shows pleomorphic cells with intracellular periodic acid - schiff positive hyaline globules section showing glandular , microcystic pattern and myxomatous stroma ( h and e , 100 ) .
inset on the left shows glands and inset on the right shows papillae ( h and e , 400 )
fine needle aspiration cytology is a useful first line of investigation to diagnose testicular masses .
it provides a triage of cases of testicular tumors into those who require surgery and those who do not .
smears are cellular with presence of cohesive clusters of very immature cells having basophilic cytoplasm and a prominent nucleolus .
presence of intra and extracellular pas positive hyaline globules and a myxoid background are characteristic features .
reported yolk sac tumor of the undescended testis which initially presented with a mass in the left lobe of the liver . in the present case ,
fnac provided a precise diagnosis of yolk sac tumor of the undescended testis which was clinically suspected to be either a renal or lymph node mass .
fnac in conjuction with raised afp levels is useful to diagnose yolk sac tumors and for planning further therapy .
sinha et al . and cox et al . reported similar cases of yolk sac tumor in an undescended testis in small children .
testicular malignancy should always be ruled out when a cyrptorchid child presents with an abdominal mass .
mixed germ cell tumors occur frequently in the testis and only one component may be sampled on fnac .
the type of components present in the mixed germ cell tumor has major implications on the prognosis of the patient .
tumor markers like afp , hcg , lactate dehydrogenase and placental like alkaline phosphatase are useful in making the diagnosis .
treatment and outcome of germ cell tumors in undescended testis is similar to those of germ cell tumors in general .
reported that survival among patients with testicular malignancy in descended and undescended testis was similar .
the present case highlights the use of fnac in diagnosing testicular masses , especially in our case where the lesion presented with multiple lymph node masses and renal hydronephrosis and was clinically and radiologically suspected to be a wilm 's tumor with metastasis or a lymphoma .
fnac is a useful , rapid and inexpensive tool , making it a first line of investigation in many hospitals .
however , mixed germ cell tumors may be missed on cytology and should be correlated with clinical and radiological findings and serum tumor markers prior to surgery .
 yolk sac tumor is the most common germ cell tumor in infants and children . 
 majority of them arise in the gonads . 
 yolk sac tumor of undescended testis has been rarely diagnosed . 
 we present a case of yolk sac tumor in right undescended testis in a 2-year - old child primarily diagnosed by fine needle aspiration cytology . 
Introduction
Case Report
Discussion
Conclusion