Keywords
extragonadal germ cell tumor - yolk sac tumor - abdominal mass - non-seminomatous
germ cell tumor - young adult
Introduction
Extragonadal germ cell tumors (EGGCTs) are a rare subset of germ cell neoplasms, accounting
for 2 to 5% of all germ cell tumors. These tumors typically arise in midline structures
such as the mediastinum and retroperitoneum, with gastrointestinal involvement being
extremely uncommon. Its origin is thought to stem from the aberrant migration of primordial
germ cells during embryogenesis.[1]
Clinical manifestations depend on tumor location, but intra-abdominal cases often
present with nonspecific symptoms, such as abdominal pain, mass effect, or intestinal
obstruction. Given their rarity, EGGCTs in the gastrointestinal tract are frequently
misdiagnosed or initially mistaken for more common pathologies such as gastrointestinal
stromal tumors or lymphomas.[2]
Diagnosis requires a high index of suspicion and relies on a combination of histopathology,
immunohistochemistry, and serum tumor markers. Yolk sac tumors, a frequent histological
variant, characteristically express alpha-fetoprotein (AFP), glypican-3, and SALL4.[3] Elevated AFP and β-human chorionic gonadotropin (β-hCG) levels are important for
both diagnosis and treatment response monitoring.
The standard treatment for non-seminomatous EGGCTs involves platinum-based chemotherapy,
primarily the bleomycin, etoposide, and cisplatin (BEP) regimen. Surgery is often
reserved for residual disease or complications, such as obstruction or bleeding.[4] Surveillance of the testes is essential to exclude metachronous or occult gonadal
diseases.[5] Given the infrequent occurrence of gastrointestinal EGGCTs, further case reporting
and literature synthesis are crucial to guide early diagnosis and evidence-based treatment.
Germ cell tumors are neoplasms derived from primordial germ cells that are typically
found in the gonads.[6]
[7] However, these tumors can also occur at extragonadal sites because of aberrant migration
of primordial germ cells during embryogenesis.[8] The most common locations for EGGCTs are the mediastinum, retroperitoneum, and pineal
gland.[9]
[10] The diagnosis of EGGCTs can be challenging because of their rarity and the wide
range of differential diagnoses that must be considered. Symptoms vary considerably
depending on the size and location of the tumor, and a significant number of individuals
remain asymptomatic.[9] Gastrointestinal stromal tumors are the most common mesenchymal tumors of the gastrointestinal
tract, and may be benign or malignant.[11] However, EGGCTs presenting as primary intestinal masses are exceedingly rare, with
only a handful of cases reported in the literature. These tumors pose a diagnostic
challenge for clinicians because of their unusual presentation and the need to differentiate
them from other, more common intestinal malignancies.
This case highlights the exceptional presentation of an EGGCT localized to the jejunum,
a seldom-involved site. Documenting such rare clinical entities adds to the current
understanding, raises diagnostic awareness, and supports timely and accurate management
in similar future cases.
Case Report
A 25-year-old male patient presented to a tertiary oncology care center with complaints
of abdominal pain, abdominal mass, and subacute intestinal obstruction for 1 month.
Vital signs on presentation were a blood pressure of 112/70 mm Hg and a pulse rate
of 90 beats per minute. Upon clinical examination, the mass in the abdomen was palpable
at approximately 8 × 9 cm in the umbilical region of the abdomen. No other physical
findings were noted. The patient underwent an emergency debulking surgery.
The complete blood count revealed total leucocyte count of 9.1 × 103/μL, absolute neutrophil count of 5.6 × 103/μL, and platelet count of 422 × 103/μL. No abnormalities were observed in liver function, renal function, or serum electrolytes.
Histopathology (jejunal mass debulking) was suggestive of poorly differentiated neoplasm
([Fig. 1]). Immunohistochemistry (jejunal mass debulking) was positive for SALL4, CK, patchy
PLAP, and AFP, suggesting an EGGCT favoring a yolk sac tumor ([Fig. 2]). Serum markers analysis demonstrated a β-hCG of 23 mIU/mL, AFP of 854 IU/mL, and
LDH of 277 U/L. Postoperative computed tomography scan of thorax, abdomen, pelvis
was done, which showed an ill-defined heterogeneously enhancing lesion. The lesion
was epicentered at the root of the mesentery and was abutting anterior abdominal wall
measuring 4.2 cm × 5.9 cm × 9 cm (AP × TR × CC), right kidney was normal, and left
kidney was measuring 7.7 cm × 8.9 cm × 12.5 cm (AP × TR × CC) with few heterogeneously
enhancing lesion with hypoenhancing areas noted in the subcapsular region of left
kidney measuring 3.9 cm × 2.8 cm. The retroperitoneum and thorax were normal ([Fig. 3]). Ultrasonography of the bilateral testes showed a normal right testis and left
testis with microcalcification ([Fig. 4]). The diagnosis of stage IIIC poor-risk non-seminomatous germ cell tumor was made
according to the IGCCCG (International Germ Cell Cancer Collaborative Group) classification.
Fig. 1 (A) Histopathological image of a yolk sac tumor demonstrates a reticular (microcystic)
growth pattern, characteristic of this malignant germ cell tumor. (B) Histopathological image of yolk sac tumor; hyaline globules are seen. (C) Histopathological image of yolk sac tumor hyaline globule and Schiller-Duval bodies.
Fig. 2 Immunohistochemistry (A) negative for CK7 and CK20 (B) diffuse membranous and cytoplasmic positive for CK (C) diffuse strong nuclear positivity for SALL4 (D) patchy positivity for AFP and PLAP.
Fig. 3 (A) CT image with cross-sectional view of jejunal mass. (B) CT image with coronal view showing jejunal mass.
Fig. 4 Ultrasound of bilateral testes showing (A) normal right testis and (B) left testis with microcalcification.
Treatment
The patient underwent a first-cycle EP because of an ECOG performance status of 2,
and PFT showed a restrictive pattern due to poor effort post-surgery, with a percentage
predicted DLCO of 45 and a percentage predicted FEV1 of 62, FVC of 58, and FEV1/FVC
of 108. After the first cycle of chemotherapy, serum marker levels showed a decreasing
trend. PFT and DLCO were repeated, which showed an improved report with a percentage
predicted DLCO of 76. The patient was started on the BEP regimen, and was scheduled
for high inguinal orchidectomy on a later date. Currently, the patient is undergoing
treatment and has completed one cycle of EP and three cycles of BEP with residual
jejunal disease of more than 1 cm postchemotherapy. Patient is asymptomatic and planned
for surgical resection of the residual abdominal mass along with a left high inguinal
orchidectomy in view of microlithiasis noted on USG, Suggestive of a burnt-out primary
tumor. Addressing the burnt-out primary is essential, as leaving it untreated increases
the risk of relapse.
Discussion
This case highlights the atypical presentation of an EGGCT in a young male with complaints
of abdominal pain and subacute intestinal obstruction. The absence of gonadal involvement
and localization to the jejunum highlights an unusual clinical scenario. Diagnosis
was established through a combination of histopathology, immunohistochemistry, and
markedly elevated serum tumor markers (AFP and β-hCG).[1]
[3] The patient responded well to platinum-based chemotherapy (EP/BEP) and was scheduled
for surgical intervention, indicating a favorable trajectory despite poor-risk staging.[4]
EGGCTs are primarily present in the mediastinum and retroperitoneum; gastrointestinal
tract involvement remains exceedingly rare. According to recent reviews, only a handful
of jejunal germ cell tumors have been reported, and most are diagnosed postsurgically
because of their overlapping presentations with GISTs or lymphomas.[9] Similar to the findings of Dieckmann and Oechsle[1] and Park et al,[2] our case highlights the difficulty in preoperative diagnosis and the crucial role
of immunohistochemistry in establishing the tumor lineage. The diagnostic challenge
in this case stemmed from the rare anatomical location and nonspecific nature of gastrointestinal
symptoms. A definitive diagnosis requires high clinical suspicion, detailed histopathological
assessment, and immunohistochemical staining for markers, such as SALL4, AFP, and
PLAP.[8] Imaging and tumor marker profiles further supported the extragonadal origin of the
tumor. Differential diagnosis included lymphoma, adenocarcinoma, and GIST.[10] This case reinforces the importance of considering EGGCTs in the differential diagnosis
of abdominal masses in young adults, even in the absence of testicular lesions. Early
diagnosis and initiation of systemic chemotherapy can improve outcomes significantly.[4] EGGCT is classified under poor risk, stating poor outcomes as compared to gonadal
GCT.[4] Reporting such rare presentations will aid in refining diagnostic algorithms and
contribute to evidence-based management protocols for EGGCTs at atypical sites.[12]
Conclusion
This is a case report of an EGGCT that presented as an abdominal mass in a young male.
Histopathological confirmation of the diagnosis is of utmost importance. Testicular
assessment should always be performed in cases of EGGCT and monitoring of the normal
testes. This strategy helps decrease the risk of metachronous testicular tumors. The
early diagnosis of EGGCT can be life-saving and has a good prognosis. The treatment
paradigms include platinum-based chemotherapy and surgery.
