Myofibromatosis
R3 吳俊璟
Terminology:
 Benign neoplasms composed of contractile myoid cells and myofibroblasts
 Congenital generalized fibromatosis, infantile myofibromatosis
 WHO classification of soft tissue tumors
 Myofibroma solitary lesion
 Myofibromatosis multicentric lesions
History
 1919, Perera, congenital multiple sarcomatosisa newborn with multiple
subcutaneous, scalp, pericardial, rib, vertebral, renal , retroperitoneal, nodal,
skeletal muscle, and splenic lesions,
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1936, Shore, spontaneous cure of a congenital recurring connective tissue
tumor tumor in subcutaneous tissue of a 6 m/o girl’s upper back
1954, Stout, juvenile fibromatoses,
1965, Kaufman and Stout, congenital mesenchymal tumors
 Solitary most common type of congenital fibrous tumor
 Multiple limited to the skin, subcutaneous soft tissue, skeletal muscle and
bone
 Generalized form involvement of major viscera such as heart wall,
pulmonary parenchyma, pleura, thyroid gland, adrenal gland, kidney,
pancreas, GI tract, mesentery, liver, and rarely the central nervous system

1981, Chung and Enzinger, AFIP(Armed Forces Institute of Pathology)
classification, infantile myofibromatosis myofibroblast: both fibroblast-like
and smooth muscle-like feature
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2002, WHO classification: myofibroma/myofibromatosis
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Epidemiology
 From newborn to old age, 90% during the first two years of life
 Solitary lesions are more common
 Most common sits: cutaneous/ subcutaneous tissues and skeletal muscles
usually of head and neck region
 Oral cavity tongue/mandible are most common sites
 Slight male predominance of 1.4 to 1.9 males: 1 female controversial
 Familial associated case: multicentric type with nonvisceral lesions greater
numbers of recurrence, but no increased mortality AD or genetic
heterogenecity
Myofibromatosis in ear
 1992, Hogan and Salassa, 43 y/o woman, recurrent benign in left external ear
canal for 3 years, erosion of bony canal wall excision with FTSG
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reconstruction
1999, Balakrishnan, 50 y/o female, left pinna swelling for 5 months, antibiotic
and excisonal biopsy recurrence, wider excision
2004, Izumaru, 38 y/o man, progressive swelling of left external auditory meatus
for 3 months excision
Histopathologic feature:
 Multinodular proliferation with a zoned configuration biphasic pattern
 Periphery: light-stained area composed of short fascicles or whorls of
myofibroblast that are spindle shaped, pale pink cytoplasm with elongated,
tapering nuclei.
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Center: dark-stained area, smaller, less differentiated, less cytoplasm and larger
basophilic nuclei; thin walled, irregularly branching hemagiopericytoma-like
vessels may develop among these cell.
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Immunohistochemical analysis: positive strong reaction to vimentin, actin and
α-SMA, negative reaction to desmin, S-100 and cytokeratin

Necrosis and calcifications in tumors in the whole body, but rare in oral
cavityspontaneous regression: most in children
Etiologic cause
 Remains unknown
 Trauma? Estrogen?
 Basic fibroblast growth factor(bFGF): a fibroblast mitogen, promote
angiogenesis and lesion growth in myofibromatosis, elevated in the acute phase
of disease
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Cytogenetic status: deletion of the long arm of chromosome 6; abnormal
chromosome 9, 16 no signature recurring chromosomal or other molecular
marker unique to myofibromatosis has been established
Differential diagnosis
 Neurogenic tumor: immunoreactivity for S-100
 Leiomyoma: immunoreactivity to desmin and h-caldesmon
 Low grade myofibroblastic sarcoma: adult, infiltrative growth pattern with
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nuclear atypia
Nodular fasciitis: mucin-rich stroma, extravasated red blood and lymphocytic
inflammation
Desmoid-type fibromatosis: more aggressive and destructive behavior, strong
immunoreactivity for beta-caenin, lack bi-phasic pattern
Fibrous histiocytoma: xanthoma cells, touton-type giant cells, associated with a
lymphocytic infiltration, positive immunorectivity to CD68
Hemangiopericytoma: immunoreactivity to CD34 and CD99
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
Infantile/ congenial fibrosarcoma: mitotic activity, invasive borders, greater
cellularity, chromosomal translocation
Clinical presentation
 Skin colored or reddish to purple dome-shape nodules, form a few millimeters to
several centimeters.
 In oral cavity: rubbery-to firm painless swelling to the affected area, superficial
and bulged or in the deeper subcutaneous area
 Duration: 2 weeks to6 months, mean 1~2 months
 Multicentric type with multiple visceral lesion poor prognosis, especially lung
involvement
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Deaths in myofibromatosis caused by mechanical compression and organ
function disruptive effects
Image study
 CT:
 Iso-attenuating with muscle, well-demarcated isodense mass that absorb
contrast
 Occasionally heterogenous mass with both multicystic and solid areas and
occasional areas of bony remodeling, calcification
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MRI:
 T1 a mass with a center that has low signal and enhancement after
gadolinium
 T2 hyperintense
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Treatment
1. Surgical excision
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Conservative surgical excision is recommended
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Biopsy is necessary
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Wide excision if rapid growth or involvement adjacent bony structure
2. Chemotherapy: for myofibromatosis that causing significant morbidity
 vinblastine and methotrexate, 2 survived,
 cyclophosphamide
 tamoxifen, vincistine, actinomycin D and cyclophosphamide
 dactinomycin, vincristine sulfate, and cyclophosphamide
3. Close follow-up
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All forms of myofibromatosis may exhibit spontaneous regression 1/2~1/3
Young children suspected of having one or more lesions biopsy, skeletal
survey, chest X-ray, ultrasound, CT of the thorax and abdomen
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References:
1. Vered M, Allon I, Buchner A, Dayan D.Clinico-pathologic correlations of
myofibroblastic tumors of the oral cavity. II. Myofibroma and myofibromatosis of
the oral soft tissues.J Oral Pathol Med. 2007 May;36(5):304-14.
2. Turner J, Skinner M, Caplan MJ, Gillespie MB.Pathology quiz case 1. Infantile
myofibromatosis. Arch Otolaryngol Head Neck Surg. 2007 Jun;133(6):620, 622-3.
3. Matthews MR, Cockerell CJ.An historic perspective of infantile myofibromatosis.
Adv Dermatol. 2006;22:279-305.
4. Koujok K, Ruiz RE, Hernandez RJ.Myofibromatosis: imaging characteristics.
Pediatr Radiol. 2005 Apr;35(4):374-80.
5. Corson MA, Reed M, Soames JV, Seymour RA.Oral myofibromatosis: an unusual
cause of gingival overgrowth.J Clin Periodontol. 2002 Nov;29(11):1048-50.
6. Foss RD, Ellis GL.Myofibromas and myofibromatosis of the oral region: A
clinicopathologic analysis of 79 cases.Oral Surg Oral Med Oral Pathol Oral
Radiol Endod. 2000 Jan;89(1):57-65.
7. Balakrishnan R, Pujary K, Shah P, Hazarika P.Solitary adult myofibroma of the
pinna.J Laryngol Otol. 1999 Feb;113(2):155-7.
8. Beck JC, Devaney KO, Weatherly RA, Koopmann CF Jr, Lesperance MM.
Pediatric myofibromatosis of the head and neck. Arch Otolaryngol Head Neck
Surg. 1999 Jan;125(1):39-44.
9. Hogan SF, Salassa JR. Recurrent adult myofibromatosis. A case report. Am J Clin
Pathol. 1992 Jun;97(6):810-4.
10. Ganly I, Patel SG, Stambuk HE, Coleman M, Ghossein R, Carlson D, Edgar M,
Shah JP. Solitary fibrous tumors of the head and neck: a clinicopathologic and
radiologic review. Arch Otolaryngol Head Neck Surg. 2006 May;132(5):517-25.
11. Izumaru S, Yoshida Y, Nakashima T. A solitary fibrous tumor in the external
auditory meatus. Auris Nasus Larynx. 2004 Mar;31(1):65-7
12. Soper JR, De Silva M.Infantile myofibromatosis: a radiological review. Pediatr
Radiol. 1993;23(3):189-94.
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