Liver and intrahepatic bile ducts - tumor
Benign tumors / conditions
Mesenchymal hamartoma

Author: Deepali Jain, M.D. (see Authors page)

Revised: 17 November 2017, last major update February 2012

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Mesenchymal hamartoma[TI] liver[TI] full text[sb]

Cite this page: Jain, D. Mesenchymal hamartoma. PathologyOutlines.com website. http://pathologyoutlines.com/topic/livertumormesenchymalhamart.html. Accessed December 17th, 2017.
Definition / general
  • Well circumscribed, solitary myxoid mass with fluid filled cysts, with architecturally abnormal bile ducts in primitive 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
Treatment
  • 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

Images hosted on other servers:

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

Microscopic (histologic) 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
Microscopic (histologic) images

Images hosted on PathOut server:

Case of the Week #61:

Various images



Images hosted on other servers:

Various images

Negative stains
Electron microscopy description
  • Myofibroblastic features
Molecular / cytogenetics description
Molecular / cytogenetics images

Images hosted on other servers:

Figures 3 and 4

Differential diagnosis