Placental site trophoblastic tumor (PSTT) is an uncommon variant of malignant gestational trophoblastic disease (GTD) that arises from intermediate trophoblast cells, producing relatively low levels of b-hCG and hPL, and are frequently resistant to chemotherapy. We report a case of PSTT with extensive pulmonary involvement and polycythemia, without known genital tract disease.
A 45-year-old woman G3P2A1 presented with a 3-month history of progressively worsening dyspnea and productive cough. She was recently discharged from another hospital after treatment for probable pneumonia. The patient denied chest pain, hemoptysis, orthopnea, night sweats or weight loss. She was sexually active with no menstrual periods for the previous 16 weeks. Last antecedent term delivery was 13 years back. She had a 30-pack-year smoking history and crack cocaine use. At presentation she was hemodynamically stable with signs of mild respiratory distress (93% SaO2 on 4L nasal oxygen). Physical examination of the lungs revealed diffuse bilateral crackles. Laboratory studies showed hemoglobin of 18 g/dl. Arterial blood gases revealed a mild respiratory alkalosis with mild hypoxemia. Chest x-ray revealed diffuse reticulo-nodular interstitial disease. Normal cardiac function was noted on a transthoracic echocardiogram. Urine drug screen was negative; LDH was 2491; HIV test was negative. CT chest revealed numerous thin-walled cysts throughout the lungs, ranging in size from a few mms to 3.5 cms, with increased density of lung parenchyma. Urine hCG was positive with a serum b-hCG of 511 mIU/mL and serum hPL of <0.10 mg/mL. A transvaginal sonogram showed fairly diffuse adenomyosis with no evidence of intrauterine or extrauterine pregnancy. Video-assisted thorascopic biopsy of the left lung was performed for further evaluation. Histological examination of the specimen revealed large cells with bizarre nuclei in a peribronchial and perivascular location. Immunoreactivity to cytokeratin, AE1/AE3, hPL, hCG and Mel-CAM was observed. HMB-45, vascular and smooth muscle markers were negative. These findings supported the diagnosis of metastatic PSTT. The patient was classified as high risk based on FIGO staging and WHO Prognostic Factors Scoring (FIGO Stage III:9). Chemotherapy with Etoposide-Methotrexate-Dactinomycin and Cyclophosphamide-Vincristine (EMA-CO) was started. However, patient expired within several cycles of chemotherapy.
PSTT commonly develops after a normal term pregnancy, abortion or molar gestation. Clinically, it presents months to years after term gestation with irregular vaginal bleeding, amenorrhea, virilization, nephrotic syndrome and rarely polycythemia. Approximately 31% have metastases at presentation, even in the absence of disease within the uterus. The lung is the most common site of metastasis, presenting as an isolated lung nodule or rarely as a pneumothorax. Serum b-hCG and hPL levels are low in relation to the tumor burden. Transvaginal ultrasound is superior to pelvic sonography in the earlier detection of uterine and extra uterine involvement. Hysterectomy is the treatment of choice when limited to the uterus. For metastatic PSTT dose-intensive, multiagent chemotherapy with EMA-CO plays an important role; however, only a partial response (28%) is seen in most patients. Salvage chemotherapy using EMA-EP (Etoposide-Methotrexate-Dactinomycin and Etoposide-Cisplatin) may be a reasonable option in recurrent disease. Single or isolated chemoresistant pulmonary metastases should be managed by thoracotomy or wedge resection of the lesions. The most common cause of death are pulmonary complications (50%). Poor prognostic indicators are; interval from antecedent pregnancy to presentation >2 years, high mitotic index (>5 mitoses/10 HPFs), metastatic disease and large tumor burden. Overall 5-yr survival for metastatic PSTT is 10–27%.
PSTT can present as extensive bilateral cystic lesions of the lung and should be suspected when there are low elevations of b-hCG levels in the setting of cystic lung disease. Although surgery is the mainstay of management, options are limited when diffuse involvement of the lung parenchyma is present.
A.A. Wani, None.