Purpose or Case Report: Cystic teratoma and lymphatic malformation (LM) are two generally benign differential considerations for congenital masses which demonstrate overlapping clinical and imaging findings. It is important to distinguish between these etiologies as cystic teratomas may require surgical excision whereas lymphatic malformations may be treated with minimally invasive sclerotherapy. We present two contrasting cases: a cervical neck teratoma mimicking a LM and an abdominal LM resembling a cystic teratoma.

Case 1: A 9-month-old female presented with a right craniofacial neck mass discovered on prenatal screening. Postnatal ultrasound demonstrated a complex multiloculated cystic lesion with peripheral vascularity. MRI confirmed a predominantly cystic, mixed soft tissue and cystic right anterolateral neck mass, most consistent with mixed type lymphatic malformation. Despite two rounds of percutaneous sclerotherapy with doxycycline, the lesion continued to enlarge on repeat MRI, crossing the midline and causing mass effect on the trachea with associated airway compromise. Respiratory distress was exacerbated by COVID-19 infection requiring intubation and eventual tracheostomy. She was started on sirolimus and underwent a third sclerotherapy treatment with doxycycline and STS without improvement. Surgical debulking was performed with pathology returning as mature multicystic teratoma composed of endodermal, neuroglial and mesodermal elements with minimal fat.

Case 2: A 13-year-old male with no significant past medical history presented with three weeks of right-sided abdominal pain and constipation. CT showed a right abdominal multiseptated cystic lesion. MRI confirmed a 27 cm multicystic abdominal mass with small soft tissue component and calcification with mass effect on the small bowel and right ureter causing partial small bowel obstruction and hydronephrosis, most consistent with a large cystic teratoma. However, following surgical excision pathology demonstrated a multicystic mass containing vascular structures with lymphocytic aggregates and nodules consistent with LM.

Expanding on these cases, this exhibit will also review the clinical presentations and management of cystic teratoma and LM with an emphasis on imaging workup and radiology-pathology correlation. It is important for radiologists and their interdisciplinary colleagues to be cognizant of the overlapping features of these conditions to avoid errors in diagnosis and management as their treatments differ.
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