Multiloculated epidermoid cyst of the liver

Congenital Epidermoid Cyst of the Liver: A Rare Entity Characterized by Antenatal Onset, Slow Postnatal Growth, and Consistent Histologic and Immunohistologic Features

BACKGROUND

There are only 15 reported hepatic epidermoid cysts; they include patients presenting congenitally through adulthood, with varied speculations about pathogenesis. Aside from recently reported pancytokeratin staining, no other descriptions have included immunohistochemistry. Splenic epidermoid cysts were recently characterized as positive for HBME-1, p63, CEA, CK7 (luminal), and CK19. We interrogate 2 hepatic epidermoid cysts with a broad panel of immunohistochemistry, with the aim of elucidating histogenesis.

METHODS

Archives were searched for "liver," "hepatic," and "cyst." Hepatic cysts lined by squamous epithelium were included. Clinical records, macroscopic findings, and hematoxylin and eosin and immunohistochemically stained slides were reviewed.

RESULTS

We identified 2 patients with epidermoid cysts of the liver, first detected on antenatal ultrasound. Both were females and asymptomatic; neither had other congenital abnormalities. Cysts enlarged slowly after birth. Resection was at ages 2 and 6 months, done to avoid potentially more difficult surgery in the future. Cysts were unilocular (4.8 cm) and multilocular (7.0 cm). Both were lined by stratified nonkeratinizing squamous to focally transitional-like epithelium and surrounded by paucicellular fibrous stroma. In the multilocular cyst, hepatocytes and fibrous stroma populated septa. Epithelium was positive for HBME-1, p63, CK19, CEA, Cam5.2, and CK7, negative for EMA, D2-40, WT-1, calretinin, and Ca19-9. Cytogenetic analysis of one showed a normal female karyotype. During the study period, 22 other pediatric liver cysts were diagnosed.

CONCLUSION

Hepatic epidermoid cyst is a distinct entity, rare but nevertheless constituting 8% of pediatric hepatic cysts at our institution. It is characterized by intrauterine onset and growth roughly commensurate with that of the fetus/infant; it is apparently unsyndromic. It may be unilocular or multilocular. It stains for an array of epithelial markers as well as HBME-1. Strong immunohistochemical overlap with splenic epidermoid cyst points to a shared pathogenesis and detracts from hypotheses that hepatic epidermoid cysts derive from hepatic elements.

Gross and histological lesions in the livers of sika deer with particular emphasis on fascioliasis

We performed gross and histological examinations of the livers of sika deer (Cervus nippon yesoensis) in Hokkaido, Japan. Out of 1,381 deer slaughtered for venison production, thickening and dilation of the large intrahepatic bile ducts and Fasciola flukes in the duct lumens were detected in 621 deer (45.0%). Furthermore, 107 non-bile lesions (75 intrahepatic and 32 capsular lesions) were detected during gross examinations. Histologically, the bile duct lesions included chronic proliferative cholangitis, papillary hyperplasia, goblet cell and pyloric gland metaplasia, and periductal fibrosis. Many of the intrahepatic non-bile duct lesions (53/75, 71%) were considered to be Fasciola fluke migration-associated lesions, including two lesion types: necrosis, hemorrhage, and eosinophilic granuloma formation (29 lesions), and lymphoid tissue formation (24 lesions). Lymphoid tissue formation was considered to result from the persistent immune responses against dead Fasciola flukes. An epidermoid liver cyst was found incidentally, which has not been reported in the veterinary literature. In summary, this study demonstrated the predominance of fascioliasis-associated lesions in sika deer livers. The gross and histological lesions caused by Fasciola flukes in sika deer were similar to fascioliasis in other animals. Moreover, we described lymphoid tissue formation as a fascioliasis-associated lesion for the first time. The fact that bile duct lesions (45.0%) had a markedly higher prevalence than fascioliasis-associated parenchymal lesions (53/1,381, 3.8%) indicated that sika deer are a permissive host for fascioliasis. Our results provide information that will aid pathological examinations of sika deer.