Mixed germ cell tumor of sacrococcygeal region; A case report with literature review

Abstract

Introduction Mixed germ cell tumors are uncommon tumors that contain two or more types of malignant, primitive, or germ cell components. This study aims to report a rare case of extragonadal mixed germ cell tumor of the sacrococcygeal area. Case report A 4-year-old female presented with lower back swelling for two weeks. It was associated with pain and fever. Investigations showed elevated Alpha-fetoprotein and normal beta HCG levels. Magnetic resonance imaging showed a large well defined heterogeneous mass at the midline of the lower coccygeal region, which displaced the rectum anteriorly without invasion. Surgical dissection of the mass with excision of the coccyx was performed. Afterward, the patient was referred to an oncology center for chemotherapy. Discussion The emergence of extragonadal germ cell tumors may be caused by a disruption in the migration of primordial germ cells along the urogenital ridge, which then undergo a malignant transformation as a consequence of their microenvironment. Another idea states that extragonadal germ cell tumors occur when germ cells that routinely migrate into the extragonadal region during embryogenesis undergo malignant transformation.

A Rare Case of Extragonadal Mixed Germ Cell Tumor of the Sacrococcygeal Region with Mature Thymic Tissue in the Teratoma Component

“…Teratoma is the most common benign histology of sacrococcygeal GCTs accounting for 32%–66%,[ 3 ] and the most common malignant histology is the yolk sac tumor, which is frequently admixed with teratoma,[ 2 ] as was present in our case.…”

“…The clinical course is unpredictable, and there is a chance of significant metastases and aggressive behavior. [ 2 ] Regular imaging is frequently used to detect sacrococcygeal germ cell tumors in utero , and if they are large enough, they may impede labor or induce hydrops fetalis. It typically presents as an external, palpable lump in newborns, but it can result in severe morbidity; therefore, any midline tumor should be examined to rule out a diagnosis of a germ cell tumor.…”

“…The treatment of mixed GCTs concentrates on the most malignant components. Complete surgical excision is the primary therapy for children with endodermal sinus tumors with adjuvant chemotherapy,[ 2 ] as was done in the current case. If tumor biomarkers return to normal, but there is a residual lump larger than 1 cm, surgery should be undertaken as in the current case.…”

“…Thus, a careful follow-up with serial AFP-level monitoring should be performed for at least 2 years. [ 2 ]…”