Cystic Biliary Atresia and Choledochal Cysts Are Distinct Histopathologic Entities

Abstract

Cystic biliary atresia (CBA), a rare cystic expansion of atretic extrahepatic bile ducts in young infants, overlaps in age at presentation and imaging features with early choledochal cysts (CC). Treatment and prognosis differ; histologic differences are unsettled. We compared 10 patients with CBA, 1975 to 2015, to an age-similar cohort of 13 infants, and to older patients who had surgery for CC. Operative details, imaging, and clinical courses were correlated to pathologic specimens. Immunostains for smooth muscle actin and myosin heavy chain were used to evaluate cyst walls and atretic segments. CBA cysts typically lacked epithelium and inflammation; cyst walls had an inner, dense cicatricial layer associated with myofibroblastic (MF) hyperplasia that often delaminated producing a grossly visible inner cyst wall. Seven proximal biliary remnants in CBA featured circumferential peribiliary MF hyperplasia/fibrosis with little or no inflammation, similar to isolated BA. Extrahepatic atresia was usually both proximal and distal to the cyst. Features in 10/13 CC from infants and 8/8 CC in older patients had mostly preserved uninjured epithelium and no subepithelial cicatrix. Mural smooth muscle (absent in CBA) was present to some extent in CC at all ages. Unexpectedly, focal MF hyperplasia and laminar sclerosis was present in a few CC in infants, resembling CBA. CBA and infant CC are distinct histologic entities that occasionally overlap. CBA bile duct injury mimics non-CBA. Cystification is an aberrant manifestation of stromal proliferation in BA. The current management approach assuming CBA and CC in infants are 2 separate disease processes is supported but caution is advised.

Inflammation, Active Fibroplasia, and End-stage Fibrosis in 172 Biliary Atresia Remnants Correlate Poorly With Age at Kasai Portoenterostomy, Visceral Heterotaxy, and Outcome

“…Based upon overall prevalence and the plausible presumption of evolution from fibroplasia to end stage obliteration, active circumferential fibroplasia is the most likely determinant of the fate of the biliary tree. The active-appearing fibroblasts in BA remnants react as myofibroblasts with antibodies to smooth muscle actin and also have been referred to as “juvenile” type compared to “mature” fibroblasts (8, 22, 23). Active fibroplasia is commonly accompanied by a variable infiltrate of mononuclear cells that defines a large subset.…”

An Unusual Case of Choledochal Cyst

“…Infantile variant of CC can mimic cystic biliary atresia in clinical presentation leading to diagnostic dilemma. 1 2 3 Biliary atresia associated with CC is also reported in literature. Here, we present an unusual case of CC that does not fit into the current classification of CCs, and can be called an atretic variant of CC.…”

“… 2 Nondilatation of intrahepatic biliary radicles and absence of biliary epithelial lining of cyst; differentiates cystic biliary atresia from CC in infants. 1 2 Contrary to CC, cystic biliary atresia does not have any continuity with biliary tree and aspirate of cyst is nonbilious. HIDA scan in cystic biliary atresia does not reveal any excretion of radioisotope into the gut.…”

Neonatal cholestasis: recent insights

“…Before surgical intervention, the precise diagnosis should be reached, as this can affect the management strategy and prognosis [23]. Intraoperative cholangiogram and pathologic examination (absence of an epithelial lining and presence of a grossly visible inner cyst wall) can effectively differentiate between both entities [24,25]. Surgical cyst excision is the treatment of choice [20].…”