Prenatal detection of disseminated extrarenal malignant rhabdoid tumor with placental metastases.

Abstract

Malignant rhabdoid tumor (MRT) is one of the rarest yet most aggressive malignancies in infants and children1. Even more rarely, MRT can be congenital, and some patients may present with metastatic disease2. We report a case of prenatally detected disseminated extrarenal MRT with placental metastases. A 37-year-old woman, gravida 2, para 1, presented for third-trimester fetal growth ultrasound assessment at 35 weeks' gestation and was diagnosed with a fetal left shoulder mass. Family history was non-contributory, and prenatal work-up was otherwise unremarkable. On referral at 36 weeks' gestation, ultrasound examination (Figure 1) corroborated the presence of the vascular mass in the left upper extremity, superficial to and anterolaterally displacing the scapula and extending into the left axilla. There were irregular margins, few cystic spaces and superficial skin breakdown. Vascular supply was from the left axillary artery. Additional findings included 1–2 cm soft tissue masses in both thighs and left inguinal region, polyhydramnios (amniotic fluid index of 31 cm), right ventricular (RV) hypertrophy and mild RV dilation. A fetal echocardiogram revealed mildly elevated combined cardiac output of 609–620 mL/min/kg. Subsequent fetal magnetic resonance imaging (MRI) further identified a right retro-orbital mass causing mild proptosis, a subcutaneous mass superficial to the right gluteal muscles and non-specific signal abnormality in both lungs (Figure 2). Differential diagnosis included myofibromatosis, congenital fibrosarcoma and rhabdomyosarcoma. Due to suspicion of fetal distress, a Cesarean section was performed at 36 + 2 weeks. Physical examination at birth verified the mass over the left scapula (Figure S1) and smaller 1–2 cm soft tissue masses on the right buttock and both thighs anteriorly. An excisional biopsy of the left thigh mass revealed integrase interactor-1 (INI-1)-negative sheets of epithelioid cells consistent with congenital extrarenal MRT. Placental microscopic examination demonstrated metastatic cells invading the villous stroma showing similar morphology to that of the original tumor (Figure S2). Given the worsening respiratory status and progressive disease despite chemotherapy, the family opted for comfort care only and the baby died on day 8 postpartum. Autopsy was recommended but declined. A 40-year review included 72 cases of congenital MRT, 12 of which were diagnosed prenatally1. Considering its aggressive nature, prenatal detection of MRT can have a significant impact on both maternal and fetal wellbeing. Identification is usually during the third trimester and based on ultrasound features including heterogeneity, mixed density, vascularization and local infiltration of the lesion in addition to polyhydramnios3; however, diagnosis based on imaging remains a challenge. In our case, fetal MRI proved valuable to determine the extent of the disease. Other factors including disseminated disease at presentation, rapid growth and increased combined cardiac output, as in our case, may be useful to raise the suspicion of malignancy. Fetal malignancies with placental metastases are exceedingly rare. To our knowledge, this case represents the seventh documented case of placental villous infiltration by a congenital MRT, and within this select group the first to arise from the fetal shoulder4. Involvement of the maternal side of the placenta by fetal neoplasms has been reported previously5. The implications of this finding are uncertain, and transit of tumor cells causing maternal disease cannot be ruled out entirely. Consequently, counseling parents regarding monitoring alternatives is warranted. Figure S1 Postnatal macroscopic view of left shoulder mass. Figure S2 Microscopic features of the rhabdoid tumor revealed by thigh (a,b) and placental (c,d) biopsies. (a) Cohesive sheets of tumor cells showing vesicular nuclei and prominent nucleoli. (b) The integrase interactor-1 (INI-1) immunohistochemical stain is negative in the tumor cells. (c) Tumor cells invading the villous stroma in the placenta showing similar morphology to the original tumor. (d) INI-1 immunohistochemical stain performed in the placental tumor is negative in the tumor cells. Background villous stromal cells showing retention of the INI-1 expression (*). Hematoxylin and eosin at × 400 magnification (a,c); INI-1 antibody, DAB, immunohistochemical stain × 400 magnification (b,d). Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.