Infantile Digital Fibroma/Fibromatosis

Abstract

The clinicopathologic and immunohistochemical features of 69 pediatric examples of infantile digital fibroma/fibromatosis (IDF) were analyzed. Thirty males, 26 females, and 1 child (sex unstated) ranging from newborn to 120 months of age (median, 12 mo) manifested 74 lesions (5 identified in follow-up) involving the toe or finger (n=71) and the hand or foot (n=3). Tumors ranged in size from 3 to 35 (median, 10) mm. All but 4 study members presented with a solitary lesion. Metachronous IDFs developed in 7 patients within 17 to 82 months. Microscopically, a cytologically bland, fibroproliferative lesion was observed forming a dome-shaped/polypoid nodule directly beneath the epidermis and invading dermal adnexa. Mitotic figures per 20 high-powered fields ranged from 0 to 7 (median, 1). Paranuclear cytoplasmic inclusions were identified in 57 tumors. Tumor cells immunohistochemically expressed calponin (11 of 11 tumors), desmin (9/9), alpha-smooth muscle actin (11/11), CD99 (11/11), CD117 (6/8), heavy caldesmon (2/11 and scattered cytoplasmic inclusions in 4 tumors), CD10 (1/9), nuclear beta-catenin (2/11), and CD34 (1/11), but not muscle actin (HUC1-1), keratins, estrogen/progesterone receptor proteins, or activated caspase-3. Twenty-eight of 38 patients (74%) experienced recurrent/persistent disease (single in 22; multiple in 6) (median, 4 mo after surgery). One recurrent tumor spontaneously regressed and the size of another remained unchanged for almost 17 years before reexcision. All 23 patients with >5 years follow-up are currently disease free (median disease-free interval, 23 y). Minor postoperative functional/cosmetic complaints were reported in 47%. No patient with adequate clinical data developed the digitocutaneous dysplasia syndrome or a conventional fibromatosis, or relayed a family history of IDF/conventional fibromatosis. Our results indicate that IDF is a unique myofibroblastic process separable from conventional fibromatoses and from histologic mimics. Conservative excision or observation after biopsy (with additional surgery employed as necessary) are recommended treatment options.

Intranodal Palisaded Myofibroblastoma

“…Studies report that trichrome histochemical staining 4,5,7,8,36 and anti-actin immunostaining 5,7,8,16,37 highlight the often times inconspicuous inclusion. Not restricted to IPM, the hyaline globule is a well-recognized hallmark of another myofibroblastic process, the infantile digital fibroma/fibromatosis 38 , and has also been described in a number of pathologically diverse myofibroblastic and smooth muscle proliferations 39 . The inclusion is believed to result from perturbations in the assemblage of actin filaments within the cytoplasm of myoid cells 39 .…”

“…Not restricted to IPM, the hyaline globule is a well-recognized hallmark of another myofibroblastic process, the infantile digital fibroma/fibromatosis 38 , and has also been described in a number of pathologically diverse myofibroblastic and smooth muscle proliferations 39 . The inclusion is believed to result from perturbations in the assemblage of actin filaments within the cytoplasm of myoid cells 39 . Michal et al 36 showed ultrastructurally that the fully developed globule in IPM consists of tightly packed actin microfilaments and, like Weiss et al 4 , noted a higher concentration of these inclusions adjacent to the collagenous bodies.…”

Congenital infantile digital fibromatosis: a case report and review of the literature

“…IDF preferentially occurs during early childhood and is present at birth in about 30% of the cases. 1 Predilection sites include the distal phalanx of the fingers and the toes. Initially IDF was considered as a potentially malignant tumor, leading to the amputation of the affected digits.…”

“…Initially IDF was considered as a potentially malignant tumor, leading to the amputation of the affected digits. 1–3 More recently several case reports of spontaneous regression suggest a benign biological behavior. 3–5 Malignant transformation and metastases have never been reported.…”

“…3–5 Malignant transformation and metastases have never been reported. 1–6 Histopathology often reveals paranuclear inclusion bodies within proliferating spindleform cells. 7 Currently conservative treatment is recommended according to the benign nature of IDF, the tendency to spontaneous regression, and the frequent recurrences after surgery.…”