NGC is usually found in the ovaries and rarely in the uterus [1]. NGC has been reported in children, particularly infants [3]. Most cases of infantile choriocarcinoma are metastasis from intraplacental choriocarcinoma to the fetus [3]. Infantile choriocarcinoma usually has an onset of 1 month [2]. Its typical symptoms include anemia, developmental delay, hepatomegaly, hemoptysis, or respiratory failure [3]. However, this was not the case for our patient. In our case, the patient presented with vaginal bleeding as the first symptom at the age of 4 years. To the best of our knowledge, our case is the first report of uterine choriocarcinoma in a child, not an infant or neonate. Currently, 30 cases of infantile choriocarcinoma have been reported [2].
Infantile choriocarcinoma is an exceedingly rare malignant tumor. In a previous study, all 30 cases of infantile choriocarcinoma revealed elevated β-hCG levels [2]. However, the diagnosis of infantile choriocarcinoma is usually incorrect because of its rarity, nonspecific imaging findings, and the absence of known maternal choriocarcinoma [4, 5]. Unfortunately, the β-hCG level in our case was not determined because of limited hospital resources. Nevertheless, immunohistochemical analysis of our case confirmed that the tumor cells expressed β-hCG in their cytoplasm (Fig. 2d).
The pathogenesis of NGC remains unclear. However, the following hypotheses have been proposed: (1) the retained totipotent germ cells undergo anomalous migration at the embryo stage, apoptosis failure occurs, and the cells change into a choriocarcinoma and (2) adult cells undergo dedifferentiation, resulting in different morphological cells, such as trophoblastic and non-trophoblastic cells [6, 7].
Of note, the diagnosis in our case was unexpectedly determined during exploratory laparotomy. The preoperative diagnosis was missed because the computed tomography (CT) scan suggested that the tumor originated from the ovarium, not the uterus (Fig. 1a). These difficulties in establishing preoperative diagnosis might be because uterine choriocarcinoma is rare and disease onset did not occur during infancy. Moreover, infantile choriocarcinoma has a very poor prognosis, and delays in diagnosis result in a high mortality rate. Without appropriate management, the patient might die within 3 weeks after the first symptoms [8]. Moreover, we were unable to perform exploratory laparoscopy or magnetic resonance imaging (MRI) because of unavailability in our institution. MRI has several advantages in evaluating pelvic mass, particularly in children, including incredible soft tissue contrast resolution and absence of ionizing radiation [9]. Furthermore, if a solid uterine mass is determined preoperatively, an ultrasound-guided tru-cut biopsy can be performed [10]. In addition, one differential diagnosis of our case is endometrial cancer (EC), since most patients with EC suffer from abnormal bleeding from the vagina [11]. However, the symptom mostly occurs during the period of post-menopause [11], which was not the case here. They suggest examining the endometrial histopathology and MRI for a precise diagnosis [11].
Our patient did not respond to chemotherapy. NGC has been reported to be resistant to chemotherapy [12, 13]. Moreover, a previous study showed that the survival rate of infantile choriocarcinoma is only 17% [2]. There is no standard treatment for NGC. Thus, NGC treatment is based on the management for GC [1]. Surgery is essential for NGC treatment since the neoplasm is derived from the patient [1].
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