Heart
Cardiac tumors - benign
Atrioventricular node tumor

Author: Nat Pernick, M.D. (see Authors page)

Revised: 19 March 2018, last major update November 2013

Copyright: (c) 2007-2018, PathologyOutlines.com, Inc.

PubMed Search: Atrioventricular node tumor

Cite this page: Pernick, N. Atrioventricular node tumor. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/hearttumormesotheliomaofAVnode.html. Accessed April 22nd, 2018.
Definition / general
  • Also called cystic tumor of AV node or mesothelioma of AV node but does not appear to have mesothelial origin
  • Rare; usually identified at autopsy
  • May be congenital rests of endodermal origin (Arch Pathol Lab Med 1990;114:1057) or ultimobranchial heterotopia identical to solid cell nests of thyroid (Am J Clin Pathol 2005;123:369)
  • Associated with other congenital anomalies
  • Often causes heart block and sudden death
  • Mean age 38 years, 75% female
  • Should examine conduction system in all patients with sudden death, particularly if a history of arrhythmia or heart block
Case reports
Radiology images

Images hosted on other servers:
Missing Image

MRI of the thorax showing tumor

Treatment
  • Pacemaker implantation, anti-arrhythmic drugs, possibly surgical excision (Heart 2000;83:E6)
Gross description
  • May not be visible due to small size (2 to 20 mm)
  • Multicystic lesion in area of atrioventricular node and membranous septum
Gross images

Images hosted on PathOut server:
Missing Image

Tumor outlined by
arrowheads (RA-right
atrium, RV-right ventricle,
TV-tricuspid valve)


Images hosted on other servers:
Missing Image

Figures 1/2: nodule
of atrioventricular
node fig 3: elastic
and trichrome stains
Microscopic (histologic) description
  • Must sample conduction system
  • Solid and cystic areas lined by nonciliated, epithelial appearing cuboidal cells (main cells), mixed with occasional clear cells (neuroendocrine or C cells)
  • Lumina contains PAS+ diastase resistant material which may calcify
  • May have inflammatory cells and fibrosis
  • No smooth muscle, no mitotic figures, no atypia
Microscopic (histologic) images

Images hosted on PathOut server:
Missing Image

Normal anatomy (no tumor) with
IAS-interatrial septum (tumors are
located inferiorly), TV-tricuspid
valve and VS-ventricular septum
Missing Image

Large cysts
filled with
proteinaceous
debris
Missing Image

Multiple small cysts not visible to naked eye

Missing Image

Cysts with irregular shape surrounded by fibrous stroma

Missing Image

Cyst may have two
cell lining, with inner
lining composed of
small cuboidal cells

Missing Image

Tumor nests and
cysts replace muscle
bundles in inferior
interatrial septum
Missing Image

Cuboidal cells and clear, sebaceous-type cells

Missing Image

Squamous differentiation and calcification of luminal debris

Missing Image

Nests of cells resembling urothelium



Images hosted on other servers:
Missing Image

H&E and AE1/AE3+

Missing Image

Cyst wall showing the large
cyst lining of simple
cuboidal epithelium
Positive stains
Electron microscopy description
  • Cells form solid nests with well formed basement membranes, cytoplasmic tonofilaments and desmosomes or glandular structures with desmosomes, electron dense material and short microvilli
Differential diagnosis