Presentation
IDF typically presents as a solitary painless, smooth, flesh-colored to red, dome-shaped nodule located on the dorsal or lateral aspect of a finger or toe but sparing the thumb or great toe; they occur principally in the first two years of life with about 1/3 of cases having a lesion since birth. However: 1) lesions with appearances similar to, and diagnosed as, IPF have been described in extra digital sites such as the arm, breast, tongue, thigh, and chest; 2) unusual cases have presented with multiple lesions, i.e. 2–3, uncommonly 7–15, and one case with 74 lesions in a 2018 review study; 3) cases have been reported in children up to the age 10 and one case was reported in a 52-year-old adult; 4) the lesions are typically smaller than 2 cm in maximum diameter but rarely have been tumor-sized, e.g. 4.5 cm; 5) the lesions, particularly when larger-sized, may be painful and/or compromise the functions of nearby joints and digits; and 6) the lesions occasionally invade the periosteum and erode a nearby bone. Pathology
Microscopic histopathological analyses of appropriately dye-stained IDF tissues typically show a non-encapsulated small tumor composed of bundles of uniform spindle-shaped cells that combine physical features of fibroblasts (the most common cell type in connective tissue) with those of myofibroblasts  (contractile, spindle-shaped cells that are identifiable by their expression of α-smooth muscle actin) in a background of collagen fibers. In hematoxylin and eosin-stained tissues, the spindle-shaped cells have pale eosinophilic (i.e.
Findings of one or a few usually small lesions centered in the dermis of a digit consisting of spindle-shaped cells and expressing α-smooth muscle actin, desmin, and calponin proteins would support the diagnosis of IDF.Infantile myofibromatosis (IMF) is, like IDF, a disease in which benign tumors develop primarily in the fingers and toes of newborns and infants and consists of spindle-shaped cells in a collagen fibrous background. IDF was once regarded as a sub-type of infantile myofibromatosis. However, IMF tumors can be far more  aggressinve than IDF lesions and consist of cells that do not have paranuclear inclusions. The World Health Organization (2020) classification includes IPF but not IMF as a tumor in the category of benign fibroblastic and myofibroblastic tumors. Treatment
Infantile digital fibroma lesions were once thought to be potentially malignant and therefore treated with surgical excision and even digital amputations. Currently, these tumors are known to be benign, may spontaneously regress, and often recur after surgical removal. Consequently, IDF lesions are usually treated by a watchful waiting observation approach with surgical resections limited to cases with functional impairment, significant symptoms, or progressive, long-term growth. Alternate or supplemental treatments used to treat IDF include injection of the glucocorticoid, triamcinolone, or the chemotherapy drug, 5-fluorouracil, directly into the lesions. Since these injection treatments have not been evaluated in large studies to date, surgical resection is the most accepted treatment of highly symptomatic or progressively enlarging IDF lesions. Overall, the prognosis for IDF is excellent. See also
Infantile fibromatosis
Skin lesion

References


== External links ==