Soft Tissue

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Lésion de l'extrémité inférieure, orteil, garçon de 7 ans.

Biopsie chirurgicale:


Lesion of the lower extremity, toe, in a 7 yo male.

Surgical biopsy:


Diagnostic proposé:










Fibromatose digitale infantile (Fibromatose à inclusions)


Proposed diagnosis:










Infantile digital fibromatosis (Inclusion body fibromatosis)

  Arguments: surlignés dans le texte ci-dessous   Clues: highligheted in the text below  
  In Rosai and Ackerman's Surgical Pathology 10th Ed  
  Infantile digital fibromatosis (inclusion body fibromatosis) is a form of fibromatosis usually restricted to childhood. The typical location is on the exterior surface of the end phalanges of the fingers and toes, but it may also occur outside the digits and at sites such as the oral cavity and breast. The lesions can be solitary or multiple and either present at birth or appear during the first 2 years of life. However, morphologically identical lesions in adults are on record. The component cells show immunoreactivity for calponin, desmin, alpha-smooth muscle actin, CD99, and CD117.  
  A distinctive microscopic feature, generally not observed in other forms of fibromatosis, is the presence of peculiar eosinophilic cytoplasmic inclusions. These have been examined ultrastructurally and found to be composed of compact masses of granules and filaments without a limiting membrane.Their significance is obscure; their similarity with the ‘virus factories’ seen in cells with certain viruses has been commented on, but they are currently thought to derive from cytoplasmic contractile proteins, probably actin. Other ultrastructural features include the presence of intracellular collagen and fibronexus, the latter being regarded as one of the most distinguishing features of myofibroblasts. Infantile digital fibromatosis has a high tendency for local recurrence.  
  Réference française dans le Séminaire des Tissus Mous (Pr. Coindre)