Soft tissue
Pericytic (perivascular)
Myofibroma / myofibromatosis


Topic Completed: 1 April 2013

Minor changes: 22 September 2020

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

PubMed Search: Myofibroma [title] soft tissue

Deepti Reddi, M.D.
Jerad M. Gardner, M.D.
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Cite this page: Reddi D, Gardner JM. Myofibroma / myofibromatosis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/softtissuemyofibroma.html. Accessed September 28th, 2020.
Definition / general
  • Benign solitary (myofibroma) or multicentric (myofibromatosis) neoplasms composed of myoid cells with thin-walled blood vessels
  • Myofibroma(tosis) is in a morphologic continuum with myopericytoma and infantile hemangiopericytoma (Clin Orthop Relat Res 2010;468:917)
Terminology
Epidemiology
  • Most common fibrous tumor of infancy
  • 60% congenital, most present before 2 years of age
  • More common in males
  • Usually solitary
Sites
  • 50% of solitary myofibromas occur in cutaneous/subcutaneous tissues of head and neck region
  • Myofibromatosis involves soft tissue and bone, more frequently occurs in deep soft tissues and may involve deep viscera
Etiology
  • Unclear, rare familial cases have autosomal dominant inheritance
Clinical features
  • Cutaneous lesions present as purple macules and resemble a vascular neoplasm
  • Subcutaneous lesions present as painless freely mobile masses
  • Deep seated lesions may be fixed
Radiology description
  • Soft tissue lesions are either well circumscribed or infiltrative, often with calcification
  • Bony lesions occur as metaphyseal radiolucent lesions with a sclerotic margin in mature lesions
Prognostic factors
  • Myofibromas can regress spontaneously
  • Less than 10% of myofibromas recur, and are cured by local re-excision
  • Extent and location of visceral lesions determine complications
  • In rare cases, extensive organ involvement causes death
  • Pulmonary involvement is a negative prognostic factor
Case reports
Treatment
Gross description
  • Median size of 2.5 cm, firm, fibrous, gray-white-brown cut surface, often central necrosis / cystic spaces with cheesy material or hemorrhage, better defined in dermis than deep soft tissue or viscera
Microscopic (histologic) description
  • Nodular or multinodular proliferation with zonal appearance
  • Peripheral zones have myoid short fascicles / whorls / nodules of plump myofibroblasts with pale pink cytoplasm and long, tapering nuclei with vesicular chromatin and 1 - 2 small nucleoli, but no atypia or pleomorphism, often associated with hyalinization, whorls / nodules can have a vaguely chondroid or chondromyxoid appearance
  • Central zones between the peripheral myoid nodules display cellular areas of round, polygonal or spindle cells with scant cytoplasm, hyperchromatic nuclei, arranged around thin walled branching ectatic "hemangiopericytic" vessels; often calcification, necrosis, hyalinization; often apparent subendothelial intravascular growth but still benign with minimal mitotic activity
Microscopic (histologic) images

Contributed by Hillary Rose Elwood, M.D.

Low power view showing well
circumscribed nodule with
variably cellular and hyalinized
pseudochondroid areas

   

Higher power views of biphasic proliferation includes immature cells in a hemangiopericytoma pattern and bundles of myofibroblastic cells



Contributed by Mark R. Wick, M.D.

Infantile type


Solitary, adult type



AFIP images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6


Fig 1: Solitary cutaneous lesion features zones of fibrous tissue with bundles of myofibroblasts and prominent thin-walled vessels
Fig 2: High power shows interface with normal collagen
Fig 3: Biphasic with immature cells in hemangiopericytoma pattern and bundles of myofibroblastic cells
Fig 4: Central hemangiopericytic area is rimmed by hyalinized myofibroblastic area
Fig 5: Junction between myofibroblastic cells and immature spindled cells
Fig 6: Myofibroblastic spindle cells and immature cells are arranged in hemangiopericytic pattern


Images hosted on other servers:

Infant lesion, arm tumor

Poorly circumscribed nodular tumor

Well circumscribed tumor


Cellular and keloid-like areas

Intracranial tumor


Myofibroblasts around capillaries and sclerosing areas

Tumor infiltrates skeletal muscle

SMA


Fascicles of myofibroblastic cells

Smooth muscle actin+

Tumor is CD34-, desmin-; vessels are CD34+ desmin+

Resembling hemangiopericytoma

Positive stains
Negative stains
Electron microscopy description
  • Continuum from fibroblasts to myofibroblasts to smooth muscle, with prominent dilated rough endoplasmic reticulum, longitudinal filament bundles with dense bodies and focal basal lamina
Differential diagnosis
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