Soft tissue
Pericytic (perivascular)
Myofibroma / myofibromatosis
Authors: Deepti Reddi, M.D., Jerad M. Gardner, M.D.
Topic Completed: 1 April 2013
Minor changes: 5 October 2020
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: Myofibroma [title] soft tissue
Table of Contents
Definition / general | Terminology | Epidemiology | Sites | Etiology | Clinical features | Radiology description | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Positive stains | Negative stains | Electron microscopy description | Differential diagnosisCite this page: Reddi D, Gardner JM. Myofibroma / myofibromatosis. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/softtissuemyofibroma.html. Accessed March 4th, 2021.
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
- Other names are infantile myofibromatosis and congenital generalized fibromatosis (Bio Med Hosp Infant Mex 2011;68:272)
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
- 63 year old man with cutaneous myofibroma of leg (Indian J Dermatol Venereol Leprol 2008;74:56)
Treatment
- Conservative excision for solitary lesions (Arch Otolaryngol Head Neck Surg 1999;125:39)
- Chemotherapy for multiple or visceral lesions (Cancer 2001;92:2692)
- Also interferon (J Pediatr Hematol Oncol 2008;30:179)
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
- S100, cytokeratin, desmin, EMA
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
- Inflammatory myofibroblastic tumor: prominent inflammation with plasma cells, no primitive cells with hemangiopericytic vascular pattern, no zonation
- Myopericytoma: predominant growth pattern is concentric perivascular arrangement of plump spindle cells (J Clin Pathol 2006;59:67); some regard myopericytoma as a spindled variant of glomus tumor
- Smooth muscle tumor: single lesion, no zonation, minimal fibrous tissue with trichrome stain (J Formos Med Assoc 2008;107:767)
