Fig. 9.1
Histological picture of infantile myofibromatosis showing uniform, elongated, fusiform, and elongated spindle-shaped cells surrounded by abundant collagen
Infantile myofibromatosis was first described by Stout in 1954 who called it congenital fibromatosis and subsequently several names were used to describe it.
The term infantile myofibromatosis however was coined by Chung and Enzinger in 1981.
Sixty percent of infantile myofibromatosis were diagnosed at or shortly after birth and 88 % occurred before 2 years of age.
Infantile myofibromatosis is a relatively rare mesenchymal tumor characterized by the appearance of nodules at different sites of the body. Commonly, it is seen in infants and neonates but there are reports of myofibromatosis occurring in older children and adults.
Commonly, it presents either as a solitary or as multiple nodules arising from the soft tissues of the head, neck, trunk, or extremities but it can affect the bones or to a lesser degree the lungs and gastrointestinal tract.
There are however reports of infantile myofibromatosis affecting unusual sites such as the brain, myocardium, pancreas, spinal cord, omentum, and larynx.
Accurate diagnosis and differentiating this from other more aggressive tumors is important.
The exact pathogenesis of infantile myofibromatosis is not known. Intrauterine estrogen exposure was suggested as a possible etiology and based on familial occurrences; a genetic cause was also proposed.
According to Enzinger and Weiss, infantile fibromatosis is classified into superficial and deep fibromatosis . Superficial tumors are usually purplish red as a result of intense vascularity. The intra-abdominal organ involvement is also known which carries worse prognosis.
Fibromatosis is a group of related conditions having the following common features: proliferation of well-differentiated fibroblasts, infiltrative pattern of growth, presence of variable amount of collagen between the proliferating cells, lack of cytological features of malignancy and scanty or absent mitotic activity, and aggressive clinical behavior characterized by repeated local recurrences but lack of capacity to metastasize distantly.
Histopathology
Diagnosis is usually made histologically.
In infantile fibromatosis , the characteristic feature is the presence of small, round intracytoplasmic inclusions . They are periodic acid–Schiff (PAS) negative and they apparently consist of actin filaments. Morphologically, these lesions occur as unicentric gray white, firm, poorly demarcated masses varying from 1 to 15 cm in the greatest dimension.
It is composed of uniform, elongated, fusiform, or spindle-shaped cells surrounded and separated by abundant collagen (Fig. 9.1).
The lack of malignant cells on histology differentiates infantile fibromatosis from infantile fibrosarcoma.
Clinical Features
Although histologically benign, this lesion tends to gradually infiltrate in skin subcutaneous tissue, muscles, nerves, blood vessels, and even bone. They are rubbery and tough.
Clinically, the presentation is of a slow-growing, firm, poorly circumscribed mass.
Clinically, there are three distinct forms of infantile myofibromatosis.
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
