Soft tissue
Fibroblastic / myofibroblastic
Fibrous hamartoma of infancy


Topic Completed: 1 July 2012

Minor changes: 23 November 2020

Copyright: 2002-2020, PathologyOutlines.com, Inc.

PubMed Search: Fibrous hamartoma of infancy

Komal Arora, M.D.
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Page views in 2020 to date: 3,662
Cite this page: Arora K. Fibrous hamartoma of infancy. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuefibroushamart.html. Accessed November 26th, 2020.
Definition / general
  • Tumor-like condition in newborns to 2 year olds
  • Poorly circumscribed proliferation of immature spindle cells in organoid pattern with fat and dense fibrocollagenous tissue
Epidemiology
  • Rare; usually age 2 years or less (25% discovered at birth), does not occur after puberty, 2/3 male
  • Usually boys
Sites
  • Axilla, shoulder and inguinal region (J Urol 1994;152:990)
  • Not hands and feet
  • Solitary, rapidly growing, freely movable mass of subcutis or dermis
Case reports
Treatment
Clinical images

Images hosted on other servers:

Axillary tumor in 6 month old boy

Scapular tumor in 7 year old girl

Scapular tumor
at surgery
showing well
developed capsule

Gross description
  • Poorly circumscribed, gray-white with yellow fat, usually 5 cm or less
Microscopic (histologic) description
  • Poorly circumscribed, organoid with 3 components:
    • Trabecular or stellate immature mesenchymal cells with scant cytoplasm and bland straight or wavy nuclei in myxoid matrix
    • Fibrocollagenous tissue composed of bland fibroblasts or myofibroblasts
    • Mature fat; overlying epidermis usually has eccrine changes, including hyperplasia, duct dilation, intraluminal papillary formations and squamous syringometaplasia (J Cutan Pathol 2007;34:39)
  • No / scant mitotic figures
Microscopic (histologic) images

AFIP images

Primitive
spindle cells
may infiltrate fat

Triphasic
pattern of
fibrous
spindle cells

Primitive and
fibrous spindle
cells are bland
and uniform



Contributed by Mark R. Wick, M.D.



Images hosted on other servers:

Three cell types

Cytology description
Positive stains
  • Vimentin (fibrous and mesenchyme areas)
  • Spindle cells in fibrous trabeculae may be actin+, desmin+
Electron microscopy description
  • Fibrous trabeculae are composed of fibroblasts and myofibroblasts, primitive mesenchymal cells have slender cytoplasmic processes with few organelles
Molecular / cytogenetics description
Differential diagnosis
Additional references
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