Home   Chapter Home   Jobs   Conferences   Fellowships   Books


Liver and intrahepatic bile ducts - Tumor

Benign tumors

Mesenchymal hamartoma

Reviewers: Deepali Jain, M.D. (see Reviewers page)
Revised: 9 January 2013, last major update February 2012
Copyright: (c) 2004-2013, PathologyOutlines.com, Inc.


● Well-circumscribed, solitary myxoid mass with fluid filled cysts, with architecturally abnormal bile ducts in prmitive myxoid stroma (Arch Pathol Lab Med 2006;130:1567)
● Third most common tumor of liver in pediatric age group (after hepatoblastoma and infantile hemangioma)
● Formerly called cavernous lymphangioadenomatoid tumor, cystic hamartoma, benign mesenchymoma

Clinical features

● 8% of pediatric liver tumors
● 75% < age 1 year; rarely adults; 60-70% male
● Right lobe predilection
● Usually asymptomatic
● Serum AFP usually normal or mildly elevated; occasionally markedly elevated
● Either neoplastic or a developmental anomaly in bile duct plate formation, possible hepatic stellate (Ito) cell origin (Pathol Res Pract. 2010;206:532)
● Rarely associated with undifferentiated embryonal sarcoma (Pediatr Dev Pathol 2001;4:482) - are pathogenetically related (Genes Chromosomes Cancer 2007;46:508)
● Adult cases are usually women with abdominal pain, more prominent fibrosis and a lesser myxoid component than childhood cases, usually no extramedullary hematopoiesis (Hum Pathol 2002;33:893)

Case reports

● 10 month old girl with cytogenetic analysis (Arch Pathol Lab Med 2006;130:1216)
● 15 month old asymptomatic boy with large hepatic mass (Case of the Week #61)


● Excision (curative, but surgery has high mortality for large masses)
● Liver transplantation may be necessary (J Clin Pathol 2006;59:542)

Gross description

● Well-circumscribed, solitary, 5-23 cm, 20% pedunculated, myxoid mass with fluid filled cysts
● May be multiloculated
● Becomes fibrotic with age
● Cysts are variable sized, contain mucoid or pink fluid with adjacent solid, pink-white areas
● May have satellite nodules; usually no necrosis, hemorrhage or calcification

Gross images

Well demarcated tumor with solid grey cut surface, slightly nodular appearance, isolated small hemorrhagic areas

Micro description

● Epithelial and mesenchymal components
● Branching bile ducts without atypia in loose, myxoid stroma with myofibroblast-like cells, dilated vessels and lymphatics
● May resemble breast fibroadenoma at low power
● Also normal appearing hepatocytes with retention of normal cell plate architecture, thick walled veins, variable collagen
● Bile ducts may have mesenchymal collars and are often cystically dilated
● Usually extramedullary hematopoiesis (90%)
● Often pools of fluid; no tumor giant cells
● Adult cases have densely hyalinized or fibrotic stroma and only focal myxoid areas

Micro images


Various images

Positive stains

● CK7, vimentin, smooth muscle actin, desmin, actin, Glypican-3 (Hum Pathol 2012;43:695)

Negative stains

● CK20

Molecular description

● Interstitial deletion near 19q13.4 (Cancer Genet Cytogenet 2004;153:60)

Molecular images

Figures 3 and 4

Electron microscopy description

● Myofibroblastic features

Differential diagnosis

● Bile duct adenoma (no hepatocyte islands) or cystadenoma (adults)
● Bile duct hamartoma: usually multiple with fibrous background
● Embryonal sarcoma: marked cellularity and atypical cells, eosinophilic PAS-D globules
● Infantile hemangioendothelioma: more vascular
● Infantile hemangioma: females more common, vascular channels of variable size
● Mixed epithelial mesenchymal hepatoblastoma: epithelial component has embryonal and fetal hepatocytes; mesenchymal component has spindle cells, osteoid, cartilage

End of Liver and intrahepatic bile ducts - Tumor > Benign tumors > Mesenchymal hamartoma

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at [email protected] with any questions (click here for other contact information).