Solitary vaginal paraganglioma with mature sacrococcygeal teratoma: a rare case report

Background Vaginal paraganglioma are rare, atypical, solitary tumors which originate from the female genital tract. Sacrococcygeal teratoma are also rare neoplasms which derive from one (or more) primordial germ cell layers. Here we report a unique case of vaginal paraganglioma with sacrococcygeal teratoma. Case presentation A 44-year-old female experienced paroxysmal hypertension, palpitations and dizziness for almost six years. Enhanced CT and MRI highlighted two abnormal soft tissue lesions located in the left vaginal wall and coccyx anteriorly, and Iodine-131 metaiodobenzylguanidine (131I-MIBG) demonstrated abnormal radioactive uptake in perineum area. Endocrine tests showed elevated plasma normetanephrine (NMN) and 24 h urine norepinephrine. There was a well-circumscribed soft tissue lesion of approximately 3.5 cm in the left lateral vaginal wall which could be palpated during bimanual examination, together with a 1.5 cm tumor in the posterior wall of the rectum. We completely resected the two lesions in stages with the support of a senior gynecologist and general surgeons. Postoperative histopathological examinations suggested the vaginal paraganglioma and mature sacrococcygeal teratoma. Targeted sanger sequencing for the 36 mostly common paraganglioma-related genes, with a depth of 1000x, revealed no mutations. Post-operatively, plasma NMN and 24 h urine norepinephrine returned to the normal range and her symptoms completely disappeared. Conclusions We reported an extremely rare case and the successful treatment of functional vaginal paraganglioma coexisting with adult sacrococcygeal teratoma. Supplementary Information The online version contains supplementary material available at 10.1186/s12902-021-00806-6.


Background
As a rare neuroendocrine tumor, paraganglioma (PG) mainly originates from neural crest cells related to the autonomic nervous system [1]. The distribution of PG is determined according to paraganglia location, ranging from the cranial base to the prostate. However, there are extremely rare cases where PG are located in the vaginal wall. There are only 10 previously reported cases to be found within the literature. Derived from the primordial germ cells and located behind the rectum, adult sacrococcygeal teratoma (SCTs) are also extremely rare with a rate of 1:40,000 to 63,000 [2]. Although most SCTs are benign, the tumor may also become malignant with an incidence up to 12 % [3]. Herein, we report a peculiar case of a patient who developed functional vaginal PG and SCT simultaneously. This is the first report of such case.

Case presentation
A 44-year-old female presented with an history of paroxysmal hypertension, dizziness and palpitations for more than six years. A vaginal tumor had been found approximately 9 months prior to presentation. Over the past six years, the patient experienced paroxysmal hypertension without definite inducement and the blood pressure could even reach 240-250 mmHg (systolic blood pressure) and 110-120 mmHg (diastolic blood pressure). These were accompanied by bouts of dizziness, palpitations, frequent nausea and vomiting. Each attack lasted approximately 10 min but subsided of their own accord. On occasion, during sexual intercourse or defecation, the aforementioned symptoms also appeared. During bimanual examination, a well-circumscribed lesion on the left vaginal wall could be palpated, at which point the patient experienced simultaneous transient hypertension with a peak systolic of 240 mmHg and diastolic of 120 mmHg. Another soft, well-defined lesion was also found on the posterior wall of the rectum. The patient denied the similar symptoms or relative neuroendocrine neoplasms in her immediate family members.
Abdominal CT scans revealed a soft-tissue density shadow measuring 3.2 cm, with obvious enhancement on the left vaginal wall (Please see Fig. 1A and B) and rectum posteriorly (Please see Fig. 3A for pertinent scans). Enhanced MRI also identified two abnormal signal neoplasms located in the vagina (Please see Fig. 2A-D) and behind the rectum (As Fig. 3B-D indicated), which appeared to be in close proximity to the tailbone (please see Fig. 3D). 131 I-MIBG examinations revealed an obvious contractive accumulation in the perineum area ( Fig. 1C and D). Endocrine tests highlighted an elevated plasma normetanephrine (NMN) level of 4.70 nmol/L (reference < 0.9nmol/L), and a 24 h urine norepinephrine (NE) of 78.32ug/24 h (reference < 40.65ug/24 h). Based upon these findings, the patient was diagnosed with paraganglioma and preoperative preparations were conducted including the administration of phenoxybenzamine 5 mg q8h, absorption of fluid and implantation of bilateral DJ tubes to protect the patient's ureters.
Through shared-decision making the patient opted for vaginal lesion resection, under direct visualization. Since the tumor located so close to the rectum and vagina, we consulted both general surgeons and a gynecologist in order to avoid damaging rectum and for vaginal reconstruction. The tumor was then successfully removed without any complications and the blood pressure during the process was quite stable. The tumor was a golden, soft but well-defined nodule measuring approximately 3.5 cm. An image has been provided, please see Fig. 4. After the operation, plasma NMN and 24 h urinary NE returned to the normal range on the second day and the symptoms ceased to occur thereafter. One week later, the patient underwent a second operation to remove the posterior rectum lesion with the assistance of general surgeons. Contrary to anticipation, the lesion appeared like a small cyst containing gelatinous substance.
Further laboratory examinations confirmed the diagnosis of vaginal paraganglioma. The immunohistochemical staining also showed SDHB (+), S100 (+), CgA (+), Syn (+), a low Ki-67 (with a proliferation index of 3 %), and AE1/AE3 (-). Please see Fig. 5 for further details. The rectal lesion had mucous glands and sebaceous structures under microscopy, drawing the diagnosis of mature SCT (see Fig. 6). As a matter of course, we also investigated 36 most common mutated genes related to PG through target sequencing; however, the results turned out to be negative (the genes were listed in supplement Table 1).

Discussion and conclusions
As a rare tumor derived from the neural crest located in the paraganglion of the autonomic nervous system, PG accounts for 10-18 % of all chromaffin tumors [4]. According to their origins, PG can be classified as either parasympathetic or sympathetic. Those with parasympathetic characteristics mainly originate from the carotid body and the tympanic cavity of the head, neck and skull base. Most parasympathetic PG did not secrete catecholamine. Sympathetic PG on the other hand, originate from the sympathetic ganglia and can be located in any part of the body from the skull base to the bladder or prostate. Most sympathetic PG are functional.
Primary vaginal paraganglioma are extremely rare with only 10 previous cases reported [1,[5][6][7][8][9][10][11][12][13]. We have provided details extracted from the previous reports. Please see Table 1 for details. Compared with paraganglioma in other regions of the body, the median age of vaginal PG appears to be younger with a median of 26 years, ranging from 11 to 66. Vaginal PG can be located in all lateral walls of vagina, although it appears that they occur most commonly in the left or right lateral wall. The diameter ranges from 1.5 to 5.0 cm. According to the few cases reported, most of the tumors were nonfunctional or static, therefore most cases were identified through routine physical or gynecological examinations, or because of irregular vaginal bleeding. Unfortunately, only three definite functional cases have been reported, which causes diagnostic uncertainty before operation [6,8,12]. Many tumors may be misdiagnosed as vaginal leiomyoma or hemangioma because of abundant blood supply. Therefore, the final diagnosis often depends on postoperative pathological examination.
Made up of endoderm, ectoderm, and mesoderm derivatives, primary teratoma mainly located in ovary, testis, anterior mediastinum, retroperitoneum, and sacrococcygeal area [14]. Adult sacrococcygeal teratoma (SCTs) is another rare tumor located behind the rectum and the embryological origin is still poorly understood. Although the classic theory regards germ cell from primitive yolk sac as the origination, others put it that the tumors may be caused by abnormal development of caudal cell mass or neural crest cells [15]. These lesions do not appear to manifest with symptoms and are therefore often found incidentally. The only common sign maybe that a patient experiences sacrococcygeal pain accompanied with constipation and frequent urination or urinary retention as the tumor progresses. In our case, the patient displayed typical symptoms of functional PG, including paroxysmal hypertension, palpitations and frequent headaches. Endocrine testing results suggested PG and radiographic images identified two possible lesions, one in vagina and the other in the rectum. Initially, we thought that both lesions were PG that led to the patient's periodic symptoms; however, the results of pathological examinations identified vaginal paraganglioma as the culprit while the SCT may be just an incidental tumor.
Surgical resection is the standard treatment for vaginal paraganglioma and every effort should be made to completely remove the tumor. However, if the tumor's  ) showed that the tumor (white arrow) was located behind the bladder, and closely related to the rectum volume is large, vaginal plasty should be considered. Vaginal paraganglioma appear to have quite favorable prognosis, and there is no report of tumor recurrence. However, we must note that this finding may be due to the limited cases and short follow-up periods, with the longest being 56 months [5]. In our case, the tumor volume was relatively large, which compressed the bladder vertically. In order to prevent bladder or ureteral injury  during operation, we implanted bilateral ureteral stents pre-operatively.
In addition, in order to decrease the risk of postoperative rectal fistula, we consulted general surgeons before the initial operation and prepared for on-the-stage consultation during operation. Sufficient preoperative preparations can ensure the safety of patients and reduce the postoperative complications. For SCTs, surgical resection of retrorectal teratoma is generally considered the optimal method due to the risk of malignant transformation [2]. Therefore, laparoscopic SCT removal has become the modern method because it is less invasive, causing a smaller wound with quicker recovery [3]. In our case, we completely removed the lesion under laparoscopy without causing any damage to the rectum.
The mechanisms of tumorigenesis of vaginal PG are still poorly understood due to the limited number of cases. In 2019, Wong et al. identified the deletion of heterozygosity in exon 1 of SDHB gene as the etiology of a young girl's vaginal PG [5]. However, in this case, we investigated 36 high-risk PG related genes including the SDH series but found no mutations. This suggested there was at least some heterogeneity in terms of the genes related to vaginal PG. The mechanisms and genes associated with SCT remain unknown, leaving huge space to be explored in the future.
In summary, we reported an extremely rare case of functional vaginal paraganglioma with adult sacrococcygeal teratoma. To the best of our knowledge, this is the first such case reported and therefore provides our experience and reflective thoughts. In order to identify related genetic mutations, we conducted target-sequencing but the result was negative. When comparing our findings with other similar instances we would suggest there is at least some heterogeneity in vaginal paraganglioma which demands further research. We could not determine whether the vaginal PG and SCT, were caused by the same etiology or whether this was purely incidental. We would encourage clinicians to record and report these peculiar cases to develop this evidence-base and to gain insight into the mechanisms involved.