Fibromatosis colli

Clinical features

  • Generally present after birth (0,4% of births), during the second until the eight week of life
  • Males more affected than females
  • Often bilateral
  • Associated with congenital anomalies-14%
  • Associated with birth injury-50%
  • In the lower third of the sternocleidomastoid

 

Fig 31a - Fibromatosis colli – Single fibroblasts, and regenerating multinucleated muscle fibres (H&E)
Fig 31b - Fibromatosis colli – Single fibroblasts, and regenerating multinucleated muscle fibres (H&E)
Fig 32 - Fibromatosis colli- fibroblasts have bland nuclei with fine chromatin (Giemsa)

 

  • Scant material
  • Bland spindle fibroblasts, single or in clusters
  • Absence of atypia
  • fibromyxoid matrix
  • Regenerating multinucleated muscle fibbers

 

Immunocytochemistry

  • Vimentin: Positive
  • Smooth muscle actin: Positive

 

Differential Diagnosis

  • Fibrosarcoma
  •  Embryonal rhabdomyosarcoma

 

Main points

  • Spontaneous regression in weeks to months
  • Torticollis can be a complication
  • Fine needle diagnosis highly recommended, since excision usually is not required
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