Choriocarcinoma, likely metastatic
Choriocarcinoma is an aggressive tumor which is of two types depending on its oncogenesis. The commoner type has a gestational origin, which is the extreme end of the spectrum of tumors classified under gestational trophoblastic diseases, hence seen exclusively in females. The other type has a germ cell origin and is part of the other germ cell neoplasms, which have their origin in totipotent cells of the gonads or embryonic cell rests. The latter type can be seen in both males and females. These tumors are aggressive and most cases present with metastases. The common sites of metastases include lung, liver and brain. Metastases in brain are usually reported as multiple haemorrhagic space occupying lesions . Choriocarcinoma amongst males is usually encountered in adolescents and young adults [3,5] with anecdotal occurrence in the elderly .
Primary extragonadal choriocarcinoma is an uncommon occurrence with site of origin being pineal gland, mediastinum and retro-peritoneum. Various hypotheses have been put forth to explain the occurrence of extragonadal choriocarcinoma which include: origin from midline primordial cell rests; metastatic choriocarcinoma with resolved gonadal choriocarcinoma and possible transformation from a non-trophoblastic tumor .
The diagnosis of choriocarcinoma in metastatic or primary brain tumor entails a pre-operative imaging to identity the site and extent of the tumor. Pre-operative diagnosis is hard to establish in absence of a known history of gestational or non-gestational choriocarcinoma. In such a case, upfront surgery helps to de-compress the haemorrhagic tumor and resolve any developing deficit. However, complete excision of the tumor is difficult due to the haemorrhagic and friable nature of the tumor. The patient can be followed up with serial serum β-HCG levels and may also benefit from a combination of chemotherapy and radiation as this tumor has proven record to being sensitive to such therapy.
The index case is unique in terms of both age of presentation and histopathological perspective. The histopathological diagnosis of choriocarcinoma starts with having a high index of suspicion, especially in primary tumors and in metastatic tumors with unknown primary. The appearance of the tumor is characteristically haemorrhagic as the malignant syncytiotrophoblasts and cytotrophoblasts cells have an inherent property of infiltration and angioinvasion. The morphology of the cells is that of a bizarre nuclear cytomorphology with admixture of multi-nucleated cells and moderate amphophilic cytoplasm. The tumor cell origin can be confirmed by immunohistochemistry using antibodies against pan-cytokeratin and β-HCG. Choriocarcinoma in the index case most likely represents a metastatic lesion. Early demise of the patient underscores the aggressive behaviour of the tumor and unfortunately did not give us an opportunity to post-operatively investigate the patient to identify the primary site.
Contributed by Manoj Gopal Madakshira, MD, Kirti Gupta, MD, Apinderpreet Singh, MS, MCh, Pravin Salunke, MS, MCh