Teaching Case

The patient was admitted to the emergency department with acute lumbar pain and vomiting. The physical examination was unremarkable. An analytic study revealed anaemia and high levels of inflammatory parameters and tumour markers (beta-hCG> 700, 000 mIU/mL, AFP 88 ng/mL and LDH 1502 UI/L). Abdominal US showed a large retroperitoneal mass.

At US and MDCT studies:
- A large retroperitoneal mass (in precaval, paracaval and interaortocaval spaces) with a discreetly heterogeneous echotexture and a predominant hypodense density with peripheral hypervascularity;
- Signs of inferior vena cava invasion (contour irregularity and a solid luminal component);
- Multiple solid hepatic lesions, heterogeneous with hyperechogenicity; peripheral hypervascularity, progressive enhancement with central necrosis and wash-out;
- Multiple well-defined pulmonary solid nodules with similar TDM characteristics.
In the presented clinical setting, one of the main differential diagnoses is a germ cell tumour (GCT; gonadal with retroperitoneal spread or extragonadal). For this reason, US of testis was performed:
- A hypoechoic solid mass within the inferior half of the right testicle, with echogenic foci with posterior acoustic shadowing from calcifications and vascularisation on colour Doppler; and bilateral microlithiasis.
At orchiectomy specimen histology: a non-seminomatous germ cell tumour (NS-GCT) with a predominant component of embryonal cell carcinoma and minor of choriocarcinoma and yolk sac.

Testicular cancer is the most frequent non-hematologic malignancy in young men aged between 18 and 40 years. Family history, infertility and cryptorchidism are risk factors. There is controversy about its association with microlithiasis [1, 2]. A painless mass is the typical presentation. In the setting of a metastatic disease, systemic symptoms or abdominal/back pain can predominate [2, 3].
90-95% are germ cell tumours (GCT) with 50% being seminomas and 50% non-seminomatous germ cell tumours (NS-GCTs, more frequent in patients < 30 years of age) [1, 2].
They primarily metastasise by lymphatic drainage and sometimes homogenously, most commonly to the lungs [3] and less commonly to the liver, bone and brain. Tumours of the right testis firstly drain to nodes around the inferior vena cava (IVC) and tumours of the left testis to nodes around the aorta: a regional disease. Nodes near the junction of the spermatic vein with IVC (on the right) and left renal vein (on the left) are the first stations [1, 2, 3]. Nodal disease superior to the renal hila occurs by direct spread [3]; and above the diaphragm is metastatic. NSGTs spread randomly in the mediastinum, pulmonary hilar and to neck lymph nodes [3].
Serum markers (beta-hCG, AFP and LDH) evaluate the burden of the disease, and can predict histology [1, 2]. In this specific case, embryonal and choriocarcinoma components justify the beta-hCG elevation.
US allows diagnosis of the primary tumour, and some findings can infer histology: NS-CGTs tend to be well-defined hypoechoic and heterogeneous, with cystic spaces and/or calcifications [1, 2]. Vascularisation, although suggestive, is not specific of malignancy [2, 3]. GCT may be small or involute even with metastases (“burned-out” tumours) [1, 2]. MRI is the option of choice when the diagnosis is in doubt [1].
Staging by the TNMS system determines management. The pathologic stage (T component) depends on histology of the resected tissue. The chest/abdomen/pelvis MDCT determines N and M components [1, 2]. Patients can also be stratified according to the International Germ Cell Tumour Consensus Conference Risk Classification [2, 3].
Retroperitoneal disease staging (N0-N3) depends on size criteria: nodes of 8mm or greater in less diameter are suspicious [1, 2, 3]. Newer techniques such as lymphotropic nanoparticle-enhanced MRI are under investigation for detecting metastases in nodes smaller than 10mm [2, 3].
The prognosis depends on early diagnosis and histologic type. NS-GCTs are treated with surgery and chemotherapy [2, 3].
Being familiar with the clinical manifestations, pathophysiology and radiologic findings allows a correct diagnosis, staging and management.