LAUSR

A 27-year-old gravida 1, para 1 woman had caesarean birth 8months previously. Three months after the birth, she was admitted to a hospital with irregular vaginal bleeding. Endometrial curettage was performed and no pathological examination was done. Since irregular bleeding continued, she presented to hospital again at 7th post-caesarean month. Her serum b-hCG level was 273 mIU/ml. The endometrial curettage was repeated and pathological examination yielded GTN, in favour of choriocarcinoma. The concurrent pelvic magnetic resonance imaging demonstrated a uterine mass which was interpreted a leiomyoma measuring 4 3 cm in the posterior wall of the uterus with no other pathology (Figure 1(A)). She was referred to our hospital at 8th post-caesarean month. Her serum b-hCG value was 167 mIU/ml. Endometrium was linear, and a 4 cm lesion located very close to endometrium within the posterior wall of the uterus was seen in the transvaginal ultrasonography. The chest X-ray was normal. Since her results, relatively low b-hCG and subendometrial mass, were not compatible with choriocarcinoma, paraffin blocks of endometrial curettage were re-evaluated by a senior pathologist and the diagnosis was changed to PSTT (Figure 1(B)). Thereafter, the lesion in the posterior wall was thought as tumour. Detailed information was given to the patient. Hysterectomy was preferred as standard treatment of PSTT; besides, the patient was also informed about the risks of fertility sparing surgery. Because she wanted to know what really the mass in the posterior wall was before making the decision of hysterectomy, the lesion was excised hysteroscopically. The pathological result was PSTT. She then decided to have a hysterectomy. A preoperative PET/CT showed pathological uptakes in the uterus and right pelvic lymph nodes. Sentinel lymph node biopsy was planned. Just before the surgery, four millilitres (1.25mg/mL) of ICG was injected as divided doses into the 3and 9-o'clock positions of the cervix, 1mL deep into the stroma and 1mL submucosally on each side. Laparoscopy with ICG compatible device was done. In the right obturator fossa, a grown lymph node with ICG uptake was seen and excised (Figure 1(C)). In the left pelvic region, the sentinel lymph node was also excised. Total laparoscopic hysterectomy with bilateral salpingectomy was done. Bilateral ovaries were macroscopically normal and left in-situ. Pathological examination of the operation specimen yielded residual PSTT in the uterus but lymph nodes were not metastatic. Her b-hCG level further dropped to normal level at day 30 postoperatively. Her follow-up was done with physical examination, b-hCG levels and chest X-rays. She has survived without recurrence at 9th month postoperatively. Nearly 6% of all reported PSTTs have lymph node metastasis (Lan et al. 2010). The presence of extrauterine disease shortens survival (Baergen et al. 2006). Lan et al. have reviewed the literature and suggested following risk factors for lymph node spread in PSST: high stage, age older than 35 years, an interval of longer than 24months from the antecedent pregnancy, high levels of hCG, deep myometrial invasion, high mitotic rate (>6/ 10 HPF) and clear cytoplasm (Lan et al. 2010). Our case did not have any high-risk factor. However, she had suspicious lymph nodes in the PET/CT. Thus, we applied sentinel lymph node biopsy to show true status of lymph nodes and plan the treatment. To our knowledge, this is the first case of PSTT who had sentinel lymph node biopsy. We suggest sentinel lymph node biopsy to be a component of surgical treatment of PSTT to clarify lymph node status. This will preclude unnecessary LNDs and missing lymph node spread. If the sentinel lymph node biopsy and/or dissection are applied and reported in more cases of PSTT, accumulating data may clarify real incidence of lymph node metastasis and possible effect of LND on survival and management. There was a suggestion for staging of PSTT (Lan et al. 2010). Lymph node metastasis is not included in FIGO staging system. However, literature review showed prognostic significance of lymphatic spread. Also, in contrast to other GTNs, main therapy of PSTT is surgery. Therefore, surgical-pathologic staging system will be more appropriate in PSTT. PET/CT is helpful in many malignancies but there is limited data about its role in PSTT (Mapelli et al. 2013). Since our patient is very young and the standard treatment of PSTT is hysterectomy, we focussed on the disease spread preoperatively. PET/CT reported lymph node metastasis, which turned out to be false positive postoperatively. However, both PET/CT and sentinel node mapping with ICG could show