Choriocarcinoma Presenting with Spinal Metastasis: Case Report and Review of the Literature

Gestational trophoblastic disease (GTD) is a spectrum of cellular proliferations originating from placental villous trophoblasts. Spinal metastasis of choriocarcinoma is rare, especially after a normal pregnancy. In this paper, we present a rare case of metastatic choriocarcinoma to the lumbar spine as the first manifestation of disease. The patient underwent surgery


Introduction
After an intrauterine or an ectopic pregnancy, and more commonly after a hydatidiform mole, a malignant and aggressive neoplasm of gestational trophoblastic epithelium of the placenta known as choriocarcinoma (CC) can appear [1,2].Choriocarcinomas are cancers that develop from germ cells and resemble those cells surrounding an embryo in the uterus.Most of these cancers form inside the reproductive organs.Some originate in the testes or ovaries, especially in young adults.Others develop in the uterus following a pregnancy or miscarriage, particularly after a molar pregnancy.A few Choriocarcinomas arise in sites outside the reproductive organs and are usually found in young adults, more commonly in males [1][2][3].Choriocarcinomas have two distinct forms, a de novo non-gestational form and the more frequently seen gestational form that consists of abnormal trophoblastic cell growth and occur once in every 20,000 to 40,000 pregnancies [3].CC has a tendency for rapid hematogeneous metastasis to multiple organs.The lung and vulvo-vaginal region are the most common locations for metastasis; CC is less commonly found in the brain and liver.Metastasis to the gastrointestinal tract, kidney, breast, or bones is extremely rare [1][2][3][4][5].There are very few reports of metastasis to the spine.Herein, we report a rare case of choriocarcinoma after a normal-term pregnancy that presented primarily with spinal metastasis and metastasis to the episiotomy incision scar.

Methods and Materials
We present a rare case of metastatic choriocarcinoma to the lumbar spine as the first manifestation of disease.A 33-year-old female patient was admitted to our hospital with low back pain increasing over the previous month that irradiated bilaterally to her ankles.She also complained of bilateral calf and anterior thigh numbness and paresthesia.The pain had worsened during the preceding week.She had just experienced her first pregnancy, which was normal with an uncomplicated full-term vaginal delivery.During the postpartum course, she reported intermittent vaginal bleeding and episiotomy wound dehiscence and underwent suturing under local anesthesia.
Upon physical examination, upper and lower extremity strength and rectal sphincter function were normal.On sensory exam, decreased sensation to light touch in a distribution that approximated the bilateral L4 and L5 dermatomes was noted.Deep tendon reflexes were normal, and no long-track signs were observed.Other systemic examinations were normal except for noted erythema and bloody discharge from the episiotomy site.
A plain radiograph of the lumbar spine was normal, but magnetic resonance imaging (MRI) showed a lumbar epidural mass posterior to the body of L4 with severe thecal sac compression which was isointense on T1-weighted and hyper-intense on T2-weighted images and showed marked enhancement after gadolinium administration (Figure 1).The first diagnosis was epidural abscess due to insertion of the epidural needle used for spinal anesthesia 3 months' prior for a normal vaginal delivery.
The presentation of the neurological deficit associated with thecal sac compression was a definite indication for surgical intervention.The proposed goals consisted of posterior spinal decompression.The patient underwent spinal surgery with a midline posterior approach.After an L3-L4 laminectomy, a dark-reddish, highly-hemorrhagic, firm
The patients age at presentation range from 20 to 44 years.Eight cases undergone surgery with chemo radiotherapy.Fourteen cases had more than one site of metastases (spinal and extra spinal metastasis), and only one of them had an epidural spinal metastasis.Kuten et al. reported a case of caudaequina compression due to epidural metastatic gestation choriocarcinoma a 20-year-old woman.Complete remission and disappearance of the neurological deficit were achieved with chemotherapy and radiotherapy, allowing a subsequent normal pregnancy and delivery; the patient remained alive during the 4 years of follow-up [7].Qian reported choriocarcinoma in the cesarean scar of a 22-year-old woman [22].
However, to the best of our knowledge and based on the literature review, metastasis of choriocarcinoma to an episiotomy incision has never before been reported.
Choriocarcinomas are cancers that develop from germ cells and resemble those cells surrounding an embryo in the uterus.Most of these cancers form inside the reproductive organs.Metastatic choriocarcinoma can occur during or after any type of pregnancy, about half of the reported cases preceded by hydatiform mole, the other cases presented in ectopic pregnancy and normal pregnancy [4,7,10,11,21].Choriocarcinoma is most sensitive to chemotherapy [18], and remission rates in the nonmetastatic stage of choriocarcinoma are 98% to 100% and more than 75% even in cases of metastatic choriocarcinoma [4,8,23].Based on previous cases, the survival rate of patients with choriocarcinoma with spinal metastasis is not favorable, and chemotherapy is the treatment of choice.Decompressive surgery mass was seen posterior to the L4 body with compression on the thecal sac and was completely removed.Postoperative imaging revealed total removal of the mass lesion (Figure 2).Histopathologic examination of the mass lesion revealed two components: multinucleated cells with a dark staining cytoplasm (syncytiotrophoblasts) and mononuclear cells which had a pale staining cytoplasm (cytotrophoblasts), indicating metastatic choriocarcinoma (Figure 3).Both components are necessary for the diagnosis of choriocarcinoma.Tissue specimens from the vertebral bodies (L3 & L4) and surrounding soft tissues were normal.
In a pathologic examination, the serum Β-HCG level was found to be above 250,000 mIU/mL.A postoperative metastatic disease workup revealed a metastatic burden in the episiotomy incision.A chest and abdominopelvic CT scan, whole body bone scan, and neuraxis imaging revealed no other metastatic lesion.No metastasis was found in the lung, liver, or CNS.
The patient was referred to an oncologist, and chemotherapy was begun.During the 24-month follow-up and after chemotherapy, no recurrence or new metastasis appeared, and the serum Β-HCG level was 1.8 mIU/mL.Furthermore, the patient remained symptom free.

Discussion
Gestational trophoblastic disease (GTD) is a spectrum of cellular proliferations originating from the placental villous trophoblast and including four main clinicopathologic forms: hydatidiform mole (complete and partial), invasive mole, choriocarcinoma, and placental site trophoblastic tumor [4].Choriocarcinoma is a rare, highly malignant neoplasm of a trophoblastic origin among GTDs (1).It can  for metastatic choriocarcinoma to the spine is recommended only when rapid-onset neurologic decline appears [20].

Conclusion
We report a rare case of metastatic choriocarcinoma to the lumbar vertebral body and epidural space after an uneventful pregnancy.The interesting aspect of this case is the presentation of the disease well after delivery, so that choriocarcinoma was not among the most probable diagnoses.Metastatic choriocarcinoma is a rare differential diagnosis of low back pain after pregnancy and should be considered in differential diagnoses.Surgery has a limited role with this form of the disease, but could be considered for progressive neurologic decline.

Conflict of Interest
All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.
There is no funding or conflict of interest.
There are no financial disclosures.

Figure 1 :
Figure 1: (A) MRI showing epidural mass posterior to L4 body that is isointense on sagittal T1-weighted, (B) Iso to hyper intense on sagittal T2weighted and (C) Enhanced after gadolinium injection (D) Axial T1-weighted enhanced images shows compression of thecal sac.

Figure 3 :
Figure 3: Pathologic examination revealed two components: multinucleated cells with a dark staining cytoplasm (syncytiotrophoblasts) and mononuclear cells which had a pale staining cytoplasm (cytotrophoblasts),

Age/Sex Spinal metastasis Other metastasis Neurologic deficit Surgery Chemotherapy radiotherapy outcome
Metastatic choriocarcinoma in these patients originated from testicular mass.

Table 1 :
Literature review of 15 cases of metastatic choriocarcinoma of the spine.