Clinical History
A patient presented with chest pain and a low grade fever for which chest radiography was performed.
Imaging Findings
The patient presented in the emergency room of another hospital complaining of chest pain and a low grade fever. A chest radiograph that was taken revealed what was interpreted as a parenchyma
consolidation. His condition was diagnosed to be community acquired pneumonia, and he received antibiotic therapy, but did not improve. A repeat X-ray film showed up to three nodular opacities. A CT
examination that was performed confirmed the nodular nature of the lesions and a fine-needle aspiration cytological study when done provided the probable diagnosis of a great cell adenocarcinoma.
With the suspicion of a primary origin in the lung, the patient was sent to our hospital for a further study and treatment. A physical examination done, including exploration of the testes, was found
to be unremarkable. Laboratory levels, including tumor markers, were within normal levels. A thoracic CT again showed three nodular, lobulated, peripheral opacities involving both lungs. One of them
grew in the lumen of the right inferior lobe bronchus. An abdominal CT scan that was taken also showed the presence of some retroperitoneal enlarged lymph nodes in the para-aortic region below the
level of the left renal vein. As this seemed unusual for a presumed lung neoplasm, a sonographic examination of the scrotum was performed. The left testis appeared smaller than the right one, and
with some heterogeneity. Various clustered foci of calcification appeared in an area of hypoechogenicity that produced some retraction of the contours of the testis. A burned-out germ cell tumor of
the testis, with both retroperitoneal and lung metastasis, was suspected. Based on the histological study of a transbronchial biopsy of the endoluminal lesion, the patient was diagnosed to have
metastasis of a germ cell tumor of the embryonal carcinoma type. The histological examination results of the excised left testis showed that he had extensive parenchymal fibrosis and intratubular
hematoxyphilic and psammoma bodies, along with some foci of seminomatous intratubular germinal cell neoplasia. The patient is undergoing chemotherapy, with an initially good response of the
retroperitoneal and pulmonary involvement.
Discussion
The term “burned-out” tumor of the testis refers to a spontaneously regressed germ cell testicular tumor that clinically presents by its metastasis, usually involving the retroperitoneal
lymph nodes or the lungs. Regression can be complete or incomplete, with residual foci of an intratubular germ cell tumor, as occurred in our case. This infrequent occurrence, primarily described by
Prim in 1927, has been attributed to immunological and ischemic phenomena. Although unproven, the most accepted theory is that the high metabolic rate of the tumor makes it to outgrow its blood
supply and thus regress (1). The metastases of a regressed testicular tumor have to be differentiated from primary extragonadal germ cell tumors. These metastases constitute 3%–5% of all germ
cell tumors and can be the result of the aberrant migration of germ cells from the yolk sac, or of the persistence of pluripotential cells in primitive rests. These are associated with a worse
prognosis and may appear in the pineal gland, the mediastinum, the sacrococcygeal area and the retroperitoneum. When a germ cell tumor of the retroperitoneum is diagnosed in a male patient, an occult
or burned-out tumor of the testis must be carefully ruled out. In a recent report, Scholz et al. found pathological evidence of a small viable or burned-out neoplasm in all 25 cases in which no
testicular mass was palpated and a histology report of the testis was available (2). The authors conclude that the so-called primary extragonadal germ cell tumors of the retroperitoneum are a rare or
even non-existing entity. There are only a few reports on the sonographic appearance of this condition. The most common findings are clustered or isolated calcification, with or without acoustic
shadowing (3,4). In the six cases reported by Comiter et al. these foci corresponded, in a descending order of frequency of occurrence, to psammoma bodies (smooth intratubular laminated
calcifications), hematoxyphilic bodies (bigger, nonlaminated intratubular calcifications) or stromal (extratubular) calcifications (3). They have to be differentiated from the sparse and punctate
calcifications of testicular microlitiasis (caused by small psammoma bodies), the calcifications that can appear in tuberculous or other granulomatous orchitis, testicular infarct, undescended testis
and in cases of a previous traumatic hematoma (4,5). In burned-out tumor testes, these calcifications coexist with areas of fibrosis consisting of acellular and dense collagenous or hyaline tissue
(3) and sometimes with residual foci of intratubular germ cell neoplasm. The hypoechoic bands in our case, that contained the foci of calcium deposits, correlated with areas of fibrosis on
pathological examination. Extensive atrophy was found on the pathological evaluation of the six testes in the study done by Comiter et al. and in 54% of the clinically examined testes in the study of
Scholz et al. (2). Sonography with a high frequency probe should almost always be capable of detecting foci of calcification and, as in our case, areas of lesser echogenicity, sometimes in a
shrunken, smaller testis, on the expected side for the lymph node spread. In an appropriate clinical context, this should be enough for diagnosing regressed germ-cell tumors and, in such instances,
removal of the testis becomes necessary, because there is a persistent tumor malignancy rate of upto 50% despite treatment using chemotherapy (3,4).
Differential Diagnosis List
Testicular burned-out germ cell tumor.
Final Diagnosis
Testicular burned-out germ cell tumor.