Primary Extragonadal Germ Cell Tumors Research Articles

Primary, Nonmidline, Extragonadal, Immature Teratoma of the Palm with Axillary Nodal Metastasis: A Rare Case Report and Review of Literature

AbstractPrimary, nonmidline, extragonadal germ cell tumors are rare. Numerous hypotheses have been proposed regarding their origin. There is lack of consensus regarding their appropriate management. We report a case of an immature teratoma arising of the left palm. A 36-year-old lady presented with a recurrent left palm swelling. Histopathological features with immunohistochemical evaluation were characteristic of an immature teratoma. Alpha-fetoprotein (AFP) and lactate dehydrogenase (LDH) were elevated. She received preoperative chemotherapy with bleomycin, etoposide, cisplatin (BEP) followed by wide excision of the palm lesion and reconstruction with free latissimus dorsi flap. Postoperatively, two more cycles of BEP were given. Eight months later, she presented with large left axillary mass which showed metastatic deposits of immature teratoma on trucut biopsy. AFP and LDH were mildly elevated. On staging fluorodeoxyglucose-positron emission tomography (FDG-PET), there were no distant metastases. She received two cycles of vinblastine, ifosfamide, and cisplatin (VeIP). Postchemotherapy FDG-PET showed good metabolic response; however, the mass remained morphologically stable. Complete resection of the axillary mass was achieved with resection of a segment of axillary vein and end-to-end reanastomosis. At 12 months of follow-up the patient is disease free. This is the first report of axillary metastases in immature teratoma of the upper extremity. Axilla is a possible site of lymph node metastases in extremity teratoma. Primary extragonadal germ cell tumor should be managed with complete surgical resection and chemotherapy.

Upper gastrointestinal bleed as the initial presentation of seminoma involving the duodenum in an elderly patient with 9year follow up: A case report and literature review.

Germ cell tumors are the most common malignancies in males between 20 and 40 years. However, primary extragonadal germ cell tumors are rare and account for 2%-5% of all germ cell neoplasms in adults. Extragonadal germ cell tumors are characterized by their midline locations including pineal and suprasellar regions, mediastinum, retroperitoneum and sacrococcyx. These tumors have also been reported in rare locations such as prostate, bladder, vagina, liver and scalp. Extragonadal germ cell tumors can be primary but may also represent metastases from primary gonadal germ cell tumors. In this report we describe a case of a duodenal seminoma in a 66-year-old male with no history of testicular tumors, who presented with upper gastrointestinal bleed as the initial manifestation. He was effectively treated with chemotherapy and continues to progress well clinically, with no episodes of recurrence.

Pathological features of primary extragonadal germ cell tumor of the prostate with small round blue cell morphology

Objective: To investigate the clinicopathological features and clinical management of primary extragonadal germ cell tumor of the prostate. Methods: Two cases of primary extragonadal germ cell tumor in the prostate were collected at Fudan University Shanghai Cancer Center, in January and September 2016, respectively. Their pathological features, clinical treatments and follow-up were retrospectively analyzed. Results: The two patients were 41 and 32 years old, respectively, and both presented with obstructive symptoms of the lower urinary tract. Histologically, both cases showed small round blue cells and an invasive growth pattern. The immunohistochemistry (IHC) stains of SALL4, OCT3/4, CD117 and PLAP were all positive, while those of PSA, AR and syn were negative. Moreover, case 1 demonstrated perinuclear dot-like staining for CKpan, which might be a diagnostic pitfall. There was no evidence of disease in other areas via physical examination or radiographic studies. Based on these IHC findings and the morphology, the two cases were diagnosed as primary seminoma of the prostate, which were consequently treated with six cycles of bleomycin, etoposide and cisplatin-based chemotherapy. A complete response was achieved in case 1. Case 2 was followed up and showed tumor recurrence, and progression with elevated tumor marker AFP. The subsequent radical removed specimens of case 2 were finally diagnosed as mixed germ cell tumor of the prostate. Conclusion: As a rare neoplastic entity, primary germ cell tumor of the prostate can show small blue round cell morphology. Pathologically, the morphology of small round blue cells combined with a perinuclear dot-like pattern of CKpan IHC staining may be a diagnostic pitfall. The clinical treatment strategy should be evaluated with consideration of the pathological diagnosis and comprehensive evaluation of the tumor markers.

Late testicular relapse two decades after primary extragonadal germ cell tumor with uncommon metastases: a case report

BackgroundExtragonadal germ cell tumor (EGCT) is a relatively rare condition, reportedly representing 3–7% of all germ cell tumors. We report a patient who had metachronous testicular tumor with uncommon metastases 20 years after primary retroperitoneal EGCT treatment, along with a corresponding literature review.Case presentationA 49-year-old Japanese man visited our department in November 2017 with chief complaints of indolent right scrotum enlargement and a right inguinal mass. History showed that the patient visited our department of gastroenterology with chief complaints of blackish feces and ill complexion in February 1997. Computed tomography (CT) showed a right retroperitoneal tumor, which was removed in the same month. Histopathological examination showed a teratoma and yolk sac tumor. He was diagnosed with primary retroperitoneal EGCT and received three courses of chemotherapy (bleomycin/etoposide/cisplatin; BEP). Periodic imaging and the determination of tumor markers (alpha-fetoprotein [AFP], human chorionic gonadotropin [HCG], and lactate dehydrogenase [LDH]) showed no recurrence or metastasis during the 5 years postoperatively. Subsequently, he did not visit the outpatient ward. In August 1999, he underwent surgery of right hydrocele. Contrast-enhanced CT showed a 35-mm contrast effect with uneven content in the right testicle and enlarged nodes that raised suspicion for metastases in the right inguinal and right external iliac lymph nodes. All tumor markers were within normal ranges. He underwent right high orchiectomy and resection of the right inguinal lymph nodes in the same month. Histopathological findings revealed seminoma (pT1, pN2, M0, S0, and TNM stage IIB). He received postoperative chemotherapy, one course of BEP therapy, and three courses of etoposide and cisplatin therapy. Post-chemotherapy CT confirmed a complete clinical response at the right external iliac lymph nodes, and this response continued 12 months later. No recurrence or metastasis has been found so far.ConclusionsWe report a patient in whom a testicular tumor with uncommon metastases occurred 20 years after primary retroperitoneal EGCT treatment. After EGCT treatment, testicular relapses tend to occur after relatively long-term follow-up. After EGCT treatment, such patients must be closely monitored for testicular recurrences and onset of testicular tumor.

Primary Extragonadal Germ Cell Tumors in Klinefelter Syndrome: 10-Years of Experience from a Single Institute

Primary Extragonadal Germ Cell Tumors in Klinefelter Syndrome: 10-Years of Experience from a Single Institute

Pure Primary Extragonadal Yolk Sac Tumor involving stomach in a Young Child: A Case Report

Germ Cell Tumors (GCTs) constitute approximately only 3% of all malignancies in children younger than 15 years of age. Primary extragonadal GCTs constitute only 1-5% of all GCTs and a retroperitoneal site is seen only in 4% of all extragonadal GCTs. Yolk sac tumor is the predominant variant in newborns and younger children. GCTs of stomach are very very rare.We report for the first time, the presentation of a primary yolk sac tumor arising from the stomach of a small child.

Site, age, and gender distribution of extra-gonadal germ cell tumors in the US from 1973 to 2015.

e16051 Background: Germ cell tumors (GCT) commonly arise in post pubertal gonads where they are influenced by sexually dimorphic hormone signaling. More rarely, extra-gonadal GCTs (EGGCTs) arise in midline sites, coinciding with the route of primordial germ cell migration. EGGCTs are proposed to arise from cells not completing this migration. We characterized the incidence of EGGCTs according to patient and tumor features in an attempt to elucidate tumor origins. Methods: In Surveillance, Epidemiology, and End Results (SEER) Program SEER*Stat Database SEER 9 Regs Research Data, 1973-2015, primary EGGCT cases were identified by ICD-O-3 histologic types (seminoma: 9060-9062, 9064; non-seminoma 9065-9101) grouped into central nervous system (CNS), mediastinum, and other EGGCT sites. Age-specific incidences for males and females were divided into adolescents and young adults (AYA) defined by the National Cancer Institute as 15-39 years of age, and younger childhood and older adult groups. Results: In AYAs and older adults, age-adjusted incidence of males exceeded that of females at all sites (p≤0.006, all comparisons) (Table). Male incidence was highest in AYAs (all EGGCT, 4.35/1,000,000 person-years (Mpy); mediastinum, 2.17/Mpy; other 0.68/Mpy). Female incidence was highest in childhood (CNS, 0.86/Mpy; mediastinum, 0.14/Mpy; other 0.64/Mp-y). Conclusions: Patterns of EGGCT incidence differ substantially between sexes. Permissive extra-gonadal sites of males or male-predominant exposures may explain higher incidence in males. Alternatively, EGGCT precursor cells may have sex-specific features affecting malignant potential. [Table: see text]

Autologous Hematopoietic Stem Cell Transplantation for Male Germ Cell Tumors: Improved Outcomes Over 3 Decades.

The curative potential of autologous hematopoietic cell transplantation (autoHCT) for male germ cell tumors (GCTs) is well established. The optimal timing and number (single transplant [ST] versus tandem transplants [TT] versus triple transplants) of autoHCT are controversial, with wide practice variations. We examined survival trends among 2395 recipients of autoHCT for male GCTs between 1990 and 2015 reported to the Center for International Blood and Marrow Transplant Research. Trends and outcomes were analyzed by year of transplantation for intervals 1990 to 1994 (N = 288), 1995 to 1999 (N = 351), 2000 to 2004 (N = 376), 2005 to 2009 (N = 509), and 2010 to 2015 (N = 871). Multivariate analysis was restricted to the subset from 2000 to 2015 with research-level data (n = 267). The median duration of follow-up was 51 months. The median age at autoHCT was 31 years; 633 patients (26%) had primary extragonadal GCT, and 1167 (49%) underwent TT. The 3-year progression-free (PFS) and overall survival (OS) improved from 24% (95% confidence interval [CI], 18% to 31%) and 35% (95% CI, 29% to 40%), respectively, in 1990 to 1994 to 47% (95% CI, 43% to 50%) and 54% (95% CI, 50% to 57%), respectively, in 2010 to 2015 (P <.0001). TT recipients were more likely than ST recipients to undergo autoHCT as first salvage treatment. The proportion of TTs increased from 38% of all autoHCTs in 2000 to 2004 to 77% in 2010 to 2015. Nonseminoma histology, residual disease at autoHCT, >1 line of pretransplantation chemotherapy, and ST versus TT were associated with inferior PFS and OS. Post-transplantation survival has improved significantly over time for relapsed/refractory male GCT and is associated with the increased use of TTs (compared with STs) and performance of autoHCT earlier in the disease course.

A novel pathology of a mediastinal neoplasm

Primary extragonadal malignant germ cell tumors (EMGCTs) are rare and account for only 2–5% of malignant germ cell tumors. Vascular tumors are uncommon mediastinal masses making up < 1% of all mediastinal masses. We report the case of a 20-year-old man presenting with a germ cell seminoma as well as an atypical hemangioma encapsulated in one mass within the mediastinum. This clinical report focuses on a 20-year-old man who presented with both a germ cell seminoma as well as an atypical hemangioma within one encapsulated mass, a unique case not presented before in literature to our knowledge. The histological analysis is essential in correctly diagnosing a neoplasm. Combining the unique histology of this case with the clinical and scientific knowledge of several specialties allowed the clinicians to successfully develop a treatment for this patient.

Tandem high-dose chemotherapy and autologous hematopoietic stem cell transplantation (SCT) compared to single SCT for relapsed/refractory germ cell tumors (GCT).

572 Background: Single-center observational studies have established the use of single or tandem SCT to salvage relapsed GCT but randomized trials are lacking. We analyzed outcomes and prognostic factors in 2,395 male SCT recipients for relapsed GCT between 1990 and 2015. Methods: Recipients of single or tandem SCT reported to the Center for International Blood and Marrow Transplant Research were identified. Outcomes were compared by SCT year: 1990-94 (N = 288), 1995-99 (N = 351), 2000-04 (N = 376), 2005-09 (N = 509) and 2010-15 (N = 871). A recent subset (n = 267, 2000-2015) with detailed disease- and transplant-related data was further analyzed with a multivariate (MVA) Cox proportional hazards model. Results: Median age at SCT was 31 (11-76) years and 49% received SCT within 12 months of diagnosis consistent with early relapse/primary refractory GCT. 26% had primary extragonadal GCT; 1,167 (49%) had intent to tandem transplant (TT). The median follow up was 51 (3-313) months. Day 100 non-relapse mortality was statistically similar at 8% in 1990-94 (vs. 4% in 2010-15) but 3-year progression-free survival (PFS) improved from 24 (18-31)% in 1990-94 to 47 (43-50)% in 2010-15 (p &lt; 0.0001) and 3-year survival (OS) from 35 (29-40)% to 54 (50-57)% in 2010-15 (p &lt; 0.0001). Compared with single SCT, TT recipients were younger 31 (16-62) vs 34 (13-76), with lower Hematopoietic Cell Transplantation-Comorbidity Index, more likely to undergo SCT after 1 line of chemotherapy (28% vs 9%), and within 1 year of diagnosis (51% vs 38%). TT was preferred over single SCT over time (48% of SCT were TT in 2000-04 vs. 81% in 2010-15). In MVA, non-seminoma histology, residual tumor at SCT, receipt of &gt; 1 line of pre-SCT chemotherapy and single SCT (vs. TT), were associated with worse PFS and OS. Year of SCT was not significant when adjusted for these covariates. Conclusions: In this large longitudinal cohort, improvements in PFS and OS were observed in recent years. SCT earlier in disease course and tandem SCT were associated with superior outcomes. These data involving a large cohort reported from 225 centers confirm specialized centers’ date in a real-world setting.

Primary malignant teratoma of the mediastinum with poor outcome: A case report

Introduction. About 5%?10% of mediastinal tumors in adults are teratomas and about 85% of them are benign. Case report. We report a case of extragonadal malignant teratoma in a 39-year old man. The computed tomography (CT) scan of the chest revealed the soft-tissue density mass in the middle lobe of the lung. The posterolateral thoracotomy was performed and a mediastinal tumor of 25 cm was completely resected. Histopathological findings confirmed malignant teratoma. One month after the resection the positron emission tomography- computed tomography (PET/CT) scan of the whole body was performed and showed progression of the disease. Patient developed signs of the superior vena cava obstruction and received radiotherapy of the mediastinum and the metastatic lesion of the lumbal vertebra. After radiotherapy, the patient developed paraplegia and urinary incontinence and received the best supportive treatment. Conclusion. Primary extragonadal germ cell tumors have poor prognosis due to their relative chemoresistance and frequent findings of advanced disease after establishing the diagnosis.

Primary extragonadal germ cell tumor: A case report on prostate seminoma.

Primary extragonadal germ cell tumors are rare, and 60% of such cases are seminomas. While the tumors can occur in the mediastinum, thymus, retroperitoneal organs and pineal gland, seminoma originating in the prostate tissue is extremely rare. The present study reports the case of a 54-year-old male with prostate seminoma. The patient was followed up at the First Affiliated Hospital of Dalian Medical University (Dalian, Liaoning, China) from 2001 onwards. The patient received chemotherapy with cyclophosphamide following total resection of the pelvic organs, pelvic lymph node dissection, continent detenial cecum-ascending colic bladder and orchidectomy. The patient experienced considerable post-operative quality of life for >10 years and the disease did not reappear. The study indicated that extragonadal seminoma is sensitive to chemotherapy, and that radical surgery and post-operative adjuvant chemotherapy with cyclophosphamide is a reasonable and feasible treatment method.

Two Cases of Retroperitoneal Metastasis from a Completely Regressed Burned-Out Testicular Cancer

Primary extragonadal germ cell tumors (EGCT) are rare and it is still a matter of debate if they have to be considered as primary extragonadal issues or metastases from a primary testicular neoplasm. We describe two cases of the so-called burned-out seminoma, a primary testicular germ-cell tumor that spontaneously regressed after demonstration of retroperitoneal metastases. Two patients (35 and 50 years old, respectively) presented with CT findings of retroperitoneal masses. In both cases physical examination of the testis was not suspicious, and only scrotal ultrasound (SUS) showed parenchymal alterations such as scarring, calcifications and nodular lesions. Left orchiectomy and chemotherapy were then performed in both cases. Currently, they are both free of disease. Although primary germ cell tumors may be of retroperitoneal origin, the likelihood of metastasis from a testicular primary origin should always be carefully considered in order to avoid misdiagnosis and to apply the best treatment schedule for the patients. Therefore, a testicular ultrasonography is mandatory in patients presenting CT findings of retroperitoneal adenopathy, even if patients are completely asymptomatic and their physical examination appears normal.

Primary retroperitoneal dysgerminoma presenting as an adrenal tumor: A case report and literature review

Primary extragonadal germ cell tumors are rare and mostly occur in young men with predominance of nonseminomatous histology. We report an undescribed case of primary retroperitoneal dysgerminoma presenting as an adrenal tumor in a 17-year-old girl. Surgery was performed on a 10 × 9.5 cm sized adrenal gland tumor and the resected tumor showed unequivocal histological features of dysgerminoma. The diagnosis was confirmed by the tumor's germ cell immunophenotype. Postoperative ultrasonography, CT and PET over a 6-month period revealed no evidence of ovarian lesion. The patient is stable, but with a suspicious residual tumor after adjuvant chemotherapy.

RNA-binding protein LIN28 is a marker for primary extragonadal germ cell tumors: an immunohistochemical study of 131 cases

LIN28 has been shown to have an important role in primordial germ cell development and malignant transformation of germ cells in mouse. In this study, we examined the immunohistochemical profile of LIN28 in 131 primary human extragonadal germ cell tumors (central nervous system (CNS) 76, mediastinum 17, sacrococcygeal region 30, pelvis 3, vagina 2, liver 1, omentum 1, and retroperitoneum 1), including the following tumors and/or components: 57 seminomas/germinomas, 10 embryonal carcinomas, 74 yolk sac tumors, 6 choriocarcinomas, 15 mature, and 13 immature teratomas. We compared LIN28 with SALL4 to assess its diagnostic value. To determine its specificity, we examined LIN28 in 406 extragonadal-non-germ cell tumors (103 carcinomas, 91 sarcomas, 9 melanomas, 12 mesotheliomas, 83 lymphomas, 9 plasmacytomas, 82 CNS tumors, and 17 thymic epithelial tumors). The staining was semi-quantitatively scored as 0 (no cell stained), 1+ (0–30%), 2+ (31–60%), 3+ (61–90%), and 4+ (>90%). LIN28 staining was seen in all seminomas/germinomas (3+ in 1 and 4+ in 56), embryonal carcinomas (4+ in all 10), and yolk sac tumors (3+ in 3 and 4+ in 71). Variable LIN28 staining was seen in 5 of 6 choriocarcinomas (1+ to 4+), 8 of 13 immature teratomas (1+ to 2+ in immature elements), and in 1 of 15 mature teratomas (1+). Only 11 of 406 non-germ cell tumors showed 1+ LIN28 staining. Therefore, LIN28 is a sensitive (100% sensitivity) marker for primary extragonadal seminomas/germinomas, embryonal carcinomas, and yolk sac tumors with high specificity. Compared with SALL4, LIN28 demonstrated a similar level of diagnostic sensitivity for seminomas/germinomas and embryonal carcinomas. For primary extragonadal yolk sac tumors, although SALL4 stained all tumors (1+ in 1, 2+ in 2, 3+ in 10, and 4+ in 61), LIN28 stained more tumor cells (mean 95 vs 90%, P=0.03) and was therefore more sensitive. For primary extragonadal yolk sac tumors, combining LIN28 and SALL4 can achieve a higher diagnostic sensitivity than either alone.

Primary retroperitoneal seminoma: an unusual cause of testicular pain

Germ cell tumours in men usually arise from the testes, with only 1–2% originating from other locations.1 These so-called primary extra-gonadal germ cell tumours (EGCTs) are rare, accounting for 0.15–0.2% of all malignancies.2 They are characterized by their midline location, and have been reported to occur anywhere from the pineal gland to the coccyx, with the commonest locations being the mediastinum and the retroperitoneum.3 Lack of awareness of this condition, together with its rarity, often results in diagnostic delay. The commonest presenting symptoms of retroperitoneal germ cell tumours (GCTs) are abdominal and back pain, but can include weight loss, night sweats, venous thrombosis and scrotal oedema among others.3 However, there have been no reported cases of testicular pain as a presenting complaint. Here we report such a case, and highlight the difficulties in diagnosis.

Posthepatische Cholestase infolge primär-extragonadaler Manifestation eines Keimzelltumors bei einem Patienten mit Favismus

In patients with glucose-6-phosphatase dehydrogenase (G6PD) deficiency (favism) jaundice is usually caused by hemolysis due to stress, infection or following the application of drugs. We report on a 74-year-old Italian with known G6PD deficiency complaining of jaundice, weight loss and abdominal pain. Physical examination revealed jaundice of the eyes. Scrotal examination by palpation and ultrasound showed no abnormalities. Serum levels of beta-human chorionic gonadotropin and alpha-fetoprotein were within normal limits, total bilirubin was extremely elevated, with predominant direct bilirubin. Abdominal ultrasound showed posthepatic blockage of bile flow with a dilated ductus hepatocholedochus (DHC) in the absence of gallstones. Enlarged, multiple contrast-stained paraaortic and retroperitoneal lymph nodes were detected by endoscopic ultrasound and magnetic resonance imaging. Due to failed endoscopic retrograde cholangiopancreatography, visualization of the biliary tree by percutaneous transhepatic cholangiography (PTC) was performed showing an occlusion of the DHC. After successful stent-implantation by PTC with decompression of the biliary tree, the jaundice disappeared. Computer tomography-guided percutaneous biopsy of a retroperitoneal lymph node was performed for histological evaluation showing a primary extragonadal nonseminomatous germ cell tumor. According to the histology (embryonic carcinoma) and clinical stage of the tumor systemic chemotherapy was initiated including cisplatin, etoposide and ifosfamide. After the first cycle of chemotherapy the patient suffered from pneumonia leading to septic shock. Twenty-seven days after admission, the patient died of multiple organ failure. Extragonadal germ-cell tumor presenting as retroperitoneal lymph nodes with obstructive jaundice has to be considered in the differential diagnosis of cholestasis.

Extragonadal retroperitoneal germ cell tumor: primary versus metastases?

Primary extragonadal germ cell tumors are rare and their histogenetic origin is not clear. We describe two cases presenting as primary retroperitoneal germ cell tumors without clinical evidence of testicular tumor. A 21 and 18 years-old patients presented retroperitoneal choriocarcinoma and yolk sac tumor, respectively. In both cases, testicular palpation was not suspicious for testicular cancer. Testicular ultrasound founded alterations in right testes. A right orchitectomy were performed and the final diagnostics were mature teratoma associated with intratubular malignant germ cell. Adult mature teratoma is infrequent and the retroperitoneal germ cell tumors should be considered to be metastases of a viable or burned-out testicular cancer.

Mixed Nonseminomatous Germ Cell Tumor Presenting as a Subcutaneous Tissue Mass

Extragonadal germ cell tumors most commonly arise in the midline of the retroperitoneum or the mediastinum. Primary tumors involving the skin are very rare. Only one case of malignant primary germ cell tumor located in the skin has been reported. We present the case of a 44-year-old white man with a primary subcutaneous mixed nonseminomatous germ cell tumor. This man had a long-lasting subcutaneous lump of the breast, which became painful. Surgery revealed 3 juxtaposed nodules. Microscopic examination showed a mixed germ cell tumor with a 90% immature teratoma component and a 10% embryonal carcinoma component. Testicular ultrasound and computed tomography of the chest, abdomen, pelvis, and brain were normal. Serum human chorionic gonadotrophin, beta-human chorionic gonadotrophin, alpha-fetoprotein, and lactate dehydrogenase were within normal ranges. A further surgical excision was performed. The patient is presently alive with no evidence of disease after a follow-up of 7 years. Review of the literature indicates that primary cutaneous extragonadal germ cell tumors usually occur as cutaneous or subcutaneous solitary nodules or as ulcerated lesions. They mainly consist of mature teratomas in children. Only 2 cases have been reported in adults.

Comparative proteome analysis of gonadal and extragonadal germ cell tumors

14530 Background: Germ cell tumors (GCTs) are the most common malignancy in young Caucasian males aged 20–40. Even though highly effective treatment strategies have been developed for the majority of patients (pts) with GCT, long term survival rate in pts with primary mediastinal non-seminomas nowadays remains below 50%. The molecular mechanism underlying the increased resistance to treatment remains elusive. Therefore, a systematic approach of global proteome analysis was used as a screening tool to compare GCT cell lines of gonadal and extragonadal origin. Methods: Comparative protein expression analysis of two GCT cell lines, NTERA2 (of gonadal origin) and NCCIT (of mediastinal origin) was performed using 2-dimensional gelelectrophoresis. Differentially expressed proteins were analyzed using matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF). Identification of proteins was performed using peptide mass-fingerprinting and NCBI/SwissProt database search. Results: On average, 761 spots on each gel were detected. Of these, 66 proteins were found to be differentially expressed in an at least in 2-fold manner. Expression of 47 proteins was found to be higher in NCCIT than in NTERA2, 19 proteins showed lower expression in NCCIT than in NTERA2. All 66 spots were analyzed, and 35 (51%) proteins were positively identified by peptid mass fingerprinting and database search. These proteins could be grouped into different categories: 9 are involved in metabolism, 5 each in protein folding and DNA-binding/transcription, 4 in cytoskeleton/cell movement, 3 in cell signaling/differentiation, and 1 each in ion transport and membrane/vesicle trafficking. Of 7 proteins, the function is currently unknown. Conclusions: This analysis demonstrates that proteomic tools are valuable in studying similarities and differences between gonadal and primary extragonadal GCTs. Further characterization and functional analysis of selected proteins is ongoing, with special emphasis on factors potentially involved in treatment resistance and sensitivity. Furthermore, the acquired proteome map of untreated cells will help to identify cellular changes occuring under different experimental conditions in vitro like induction of differentiation and response to cytotoxic treatment. No significant financial relationships to disclose.