E2570. Ciliated Hepatic Foregut Cyst: Case Series and a Review of Literature
  1. Tatsuhiro Kato; University of South Carolina School of Medicine Greenville
  2. Christine Schammel; Pathology Associates; University of South Carolina School of Medicine Greenville
  3. Hubert Fenton; Pathology Associates
  4. Steven Trocha; Prisma Health Upstate; University of South Carolina School of Medicine Greenville
  5. Aron Devane; Prisma Health Upstate; University of South Carolina School of Medicine Greenville
Ciliated hepatic foregut cyst (CHFC) is a rare benign cyst of the liver derived from the embryonic foregut epithelium. There are 68 reported cases of CHFC in the English language literature. Imaging modalities alone such as ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), are insufficient for diagnosis due to the cyst’s nonspecific imaging features. In addition to being nonspecific, levels of attenuation, intensity, and echogenicity vary among cases. A definitive diagnosis of CHFC requires histologic confirmation from fine needle aspiration (FNA), core needle biopsy, or surgical resection. While typically benign, malignant transformation into squamous cell carcinoma (SCC) has been noted particularly for large lesions. As transformation portends a poor prognosis, early detection is essential (6). We present a case of CHFC and a comprehensive review of all case reports of CHFCs in English literature. We aim to understand CHFCs through imaging, their malignant potential, and the treatment and diagnostic paradigm for optimal patient care.

Educational Goals / Teaching Points
We aim to convey the imaging features of CHFCs and the need for a biopsy for a definitive diagnosis. Participants should understand the risk of SCC and the association between size and malignant transformation in CHFCs. In addition, participants should understand the diagnostic algorithm and when to resect a histologically confirmed CHFC based on the risk of malignancy.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The most common location for a CHFC was segment 4 (37/64, 58%) and segment 5/8 (20/64, 31%). CHFCS were mainly unilocular (35/38, 91%) and nonenhancing (28/32). Imaging characteristics varied, CHFCs were mostly hyperintense on T2-weighted MRI (24/25, 96%), hypoattenuating on CT (36/41, 88%), and hypoechoic on US (30/32, 94%). The median level of attenuation was 54 HU (IQR 14.25, Range 47-80). Excisional biopsy was diagnostic in all cases (48/48). Needle core biopsy produced a diagnostic sample in 2 out of 3 cases (66%). FNA was diagnostic in 62% of cases (8/13). Squamous cell carcinoma was present in 9% of cases of CHFC (6/69), and squamous metaplasia without SCC was present in 6% of cases (4/66). Squamous transformation was associated with a larger size (median 9 cm, IQR 5.25) than CHFC without transformation (median 3, IQR 3.98, p < 0.01).

Radiologic features of CHFCs are nonspecific; therefore, a biopsy is necessary for an accurate diagnosis. If CHFC is suspected, FNA or core needle biopsy be conducted prior to excisional biopsy. Malignant transformation of CHFCs is not uncommon and understated in previous literature. The decision to resect should be based on the risk of malignancy. If CHFC is confirmed on biopsy, we recommend resection for lesions > 5 cm due to the risk of malignancy.