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Infantile Myofibromatosis: Case Report of a Solitary Hand Lesion With Emphasis on Differential Diagnosis and Management

Netscher, David T. MD*†; Eladoumikdachi, Firas MD*; Popek, Edwina J. DO

Case Reports

Infantile myofibromatosis, both solitary and multicentric types, is discussed with emphasis on the importance of diagnosing this condition correctly. Its distinctive clinical and histological characteristics are described, as are the hazards of overhasty and overly ambitious surgical intervention. Other similarly presenting fibromatous diseases of infancy and childhood are discussed, including aplasia cutis, infantile fibrosarcoma, recurring infantile digital fibromatosis, and juvenile aponeurotic fibromatosis. A case of infantile myofibromatosis, solitary type, is reported, and the two surgical procedures carried out over a 4-year period are described. The importance of histological and immunohistochemical evaluation of lesions present during the neonatal period is stressed.

*Division of Plastic Surgery, ‡Department of Pathology, Baylor College of Medicine; and the †Department of Veterans Affairs, Medical Center, Houston, TX.

Received Apr 13, 200, and

in revised form Jul 24, 2000.

Accepted for publication Jul 24, 2000.

Address correspondence and reprint requests to Dr Netscher, 6560 Fannin, Suite 800, Houston, TX 77030.

Ulcerative cutaneous lesions of the extremities with deep cicatricial deformity are unusual in neonates and infants. There are a number of fibromatous conditions that are clinically similar. Because of the widely varying prognoses and potentially different treatment strategies for these fibromatous conditions, correct diagnosis is essential in an infant who presents with a deeply seated lesion affixed to the surrounding tissues and apparently causing local destruction with cicatricial distortion and cutaneous ulceration. The diagnosis is partially based on clinical impression but also requires histological and immunohistochemical evaluation and may, on occasion, necessitate genetic testing.

The stimulus for our report and literature review is an infant with solitary infantile myofibromatosis on the dorsum of the right hand who presented during the neonatal period with ulceration and extension contractures of the wrist and fingers. Correct diagnosis allowed conservative, function-preserving resection to be combined with watchful waiting and the reasonable expectation of the lesion’s spontaneous regression. Incorrectly diagnosed, this locally aggressive lesion might have provoked a more radical surgical intervention to the functional detriment of the extremity. We distinguish the various types of fibromatous conditions with a special focus on infantile myofibromatosis, which may present in the manner just described.

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Patient Report

Our 5-year-old female patient presented at 1 year of age with a tumor involving the entire dorsum of the right hand, wrist, and distal forearm (Fig 2A), extending into the webspaces and the proximal digital phalanges. The lesion consisted of indurated, thick “scar” tissue with resulting extension contractures of both the wrist and the metacarpophalangeal (MP) joints of the fingers. Passive wrist flexion beyond the neutral position was impossible. The fingers at rest were hyperextended at the MP joints. Passive flexion of the MP joints of the index through little fingers was 30 deg, 20 deg, 10 deg, and 10 deg respectively. Two central punctate ulcerated areas drained clear fluid periodically. Radiographic evaluation showed metacarpal broadening with patchy sclerosis and periosteal reaction, raising the question of osteomyelitis, especially in view of the draining, ulcerated areas. Magnetic resonance imaging, however, demonstrated no bone necrosis.

Fig 2

Fig 2

Fig 2

Fig 2

The histological diagnosis of infantile myofibromatosis had already been made by incisional biopsies performed during the neonatal period. The baby had been seen at birth by a plastic surgeon, who provided a history of a pink, elevated, extremely firm, ulcerative lesion on the dorsum of the hand and wrist with a central zone of necrosis. When the lesion showed no sign of healing after 2 weeks, the plastic surgeon carried out incisional biopsies. Histological examination was performed at laboratories both in the child’s country of origin and in the United States, and confirmed the diagnosis. The remainder of the baby’s physical examination during the neonatal period was normal, liver and kidneys were normal on ultrasonic examination, and the chest radiograph was unremarkable.

Because of the severity of the functional deformity of the hand, release of the extension contractures was attempted. The tumor was resected incompletely from around the tendons, which were left intact although obviously embedded in tumor (Fig 2B). No attempt was made to pursue the tumor extensions between the metacarpals. The soft-tissue wound was covered with full-thickness skin grafts from bilateral groin donor sites. This thin, soft-tissue coverage allowed clinical tumor surveillance. The resected tumor was confirmed by pathologists at our institution to be infantile myofibromatosis (Fig 1). Characteristic spindle cells resembling fibroblasts and smooth muscle cells were seen histologically.

Fig 1

Fig 1

During the ensuing years, the nodularity that had always been palpable below the skin grafts disappeared. Tumor regression appeared to be complete by the time the patient reached 5 years of age, but finger flexion was still restricted by tendon adhesions and scarring (Fig 2C). At that time, extensor tenolysis and dorsal MP joint capsulotomies were performed, and soft-tissue coverage was provided by a groin pedicle flap (Figs 2D, E). Multiple, deep tissue biopsies obtained during this second surgery revealed scar tissue only with no sign of residual infantile myofibromatosis. The child underwent hand therapy and functional dynamic bracing after the second surgery, and she wears a compression glove. She shows no evidence of tumor recurrence, and she has improved hand function and aesthetic appearance when seen long term after secondary tenolysis and groin flap coverage (Fig F). Genetic karyotyping performed when the child was 5 years old was normal.

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When ulcerative, fibrotic cutaneous lesions occur in the extremities in neonates or infants, there are a variety of possible diagnoses. Aplasia cutis is a possible diagnosis for such a presentation. Apparent at birth, it heals by scarring with subsequent deformity. Infection should be considered, as should the infantile fibromatous conditions, one of which, infantile fibrosarcoma, 1 is one of the more common malignant fibrous tumors of early childhood. Infantile myofibromatosis, another possibility, is one of the most commonly occurring fibrous tumors of the neonatal period. 2,3 It follows an aggressive local course initially, then regresses spontaneously within 2 years. 2 Soft-tissue tumors represent 25% of all neoplastic diseases occurring in infants; 85% of these are benign. 1 The infantile fibromatoses have recently received some attention in the hand literature, 1,4 but the myofibromatoses have been neglected.

This condition was first described by Williams and Schrum in 1951 as “congenital fibrosarcoma,” and then in 1954 by Stout as “congenital generalized fibromatosis”. 2 Chung and Enzinger 5 coined the term infantile myofibromatosis in 1981 after reviewing 61 cases. The disease is classified as either solitary or multicentric. Both types usually will be present at birth or will appear during infancy, although they may rarely occur after 2 years of age or during adulthood. 6–8 Solitary lesions are usually cutaneous, involving the dermis and extending to subcutaneous tissue, muscle, and bone. The multicentric type is divided into the rare form that includes visceral involvement and the form that does not. 5,9 Visceral involvement carries a high morbidity and mortality rate, and may include lungs, myocardium, the gastrointestinal tract, and, rarely, the central nervous system, 6,10 with lungs and central nervous system having the worst prognosis. 8,11 The rate of malignant transformation is unknown. Histologically, intravascular lesion growth has been noted, but this feature does not seem to affect clinical behavior. 5 One third of solitary lesions involve head and neck structures; the upper extremity is the next most common anatomic site. Spontaneous regression is generally the natural history of infantile myofibromatosis lesions without visceral involvement. In rare cases, solitary lesions may be locally aggressive with slow, continuous, destructive proliferation. 11,12

Histological and immunohistochemical studies confirm the diagnosis of infantile myofibromatosis. A zoning phenomenon is present histologically. Peripheral spindle-shaped cells arranged in bundles blend centrally into less differentiated round or polygonal cells arranged in sheets. 3 The spindle cells of infantile myofibromatosis have the ultrastructural and immunohistochemical characteristics of myofibroblasts, 2,8,11 staining positive for vimentin and α-smooth muscle actin but negative for desmin. The cells are also negative for S-100 protein, allowing their differentiation from more immature histiocytes. 6,13 Progressive cell differentiation has been offered as a possible explanation for the spontaneous regression of the solitary lesions and is a hypothesis accepted more commonly than the previously proposed apoptosis. 2

The ultrastructural, histological, and immunohistochemical characteristics of infantile myofibromatosis allow its differentiation from the many other fibromatous conditions of infancy, such as neurofibromatosis, fibrosarcoma, leiomyoma/leiomyosarcoma, hemangiopericytoma, and histiocytoses, which may have very different natural histories.

Other infantile fibromatoses should be considered separate entities from the myofibromatoses, which are characterized by the presence of myofibroblasts. Most of the infantile myofibromatoses are present at birth and nearly all have developed by 1 year of age, although later presentation may rarely occur. Juvenile aponeurotic fibromatoses occur in older children and young adults, 14 usually on the palms and occasionally on the soles of the feet. These fibromatoses are foci of hyalinized collagen and centrally located foci of calcification and cartilage formation. Plain radiographs may demonstrate the spotty calcifications. Wide excision without the sacrifice of functionally important structures gives the greatest opportunity for cure. Local recurrence is frequent, but distant metastases are rare. 15 Recurring infantile digital fibromatosis usually appears during the first year of life. 16 It rarely occurs on the palms, most frequently affecting the distal or middle phalanges of the third, fourth, or fifth digits of the hand or foot, 16 and never on big toes or thumbs. Despite apparently tumor-free margins, recurrences or new primary lesions are reported in 75% of patients, 16 and spontaneous regression is rare. The surgical approach to infantile digital fibromatoses should be individualized based on lesion location and behavior.

The pathogenesis of infantile myofibromatosis is unknown. Some have suggested a relationship to intrauterine estrogen;6,8 others have suggested a genetic cause, 7,11 and familial occurrences have been reported. 13 A case of infantile myofibromatosis has been reported involving a deletion of chromosome 6 [del (6) (q12q15)]. It is thought that the deletion may represent a marker differentiating the solitary lesion form from both the multicentric type and from fibrosarcoma, and thus may be helpful diagnostically and prognostically. 7 Our patient underwent constitutional chromosomal analysis of 20 G-banded cells and showed a normal 46,XX-chromosome karyotype, and in particular did not demonstrate a macrodeletion in chromosome 6. In the absence of fluorescent in situ hybridization testing, however, submicroscopic microdeletion could not be excluded in our patient. We did not perform tumor cytogenetics.

Infantile fibrosarcoma is one of the most common malignant fibrous tumors of infancy and it usually occurs on the extremities. 1 The cells of infantile fibrosarcoma are immunoreactive for vimentin, as are the cells of infantile myofibromatosis. 1,2 Infantile fibrosarcoma tumors histologically show highly cellular interlacing fascicles and high mitotic rates, which are generally not features of infantile myofibromatosis. The treatment of choice for fibrosarcoma of infancy is complete surgical resection. Local recurrence is reported in as many as 43% of patients, although repeat surgical resection cures most recurrences. Metastases are rare. 12 Chemotherapy has been used in patients in whom the tumor is unresectable or in whom resection would result in functional disfigurement (amputation). 1 In contrast, because most cases of solitary infantile myofibromatosis regress spontaneously by the age of 2 years, neither surgery nor chemotherapy is generally recommended. Watchful waiting is advised, and surgery is reserved for those tumors that compromise vital functions.

Our patient’s tumor had compromised her hand function to the point of affecting developmental milestones such as crawling and grasping. A multistep surgical plan was devised with the goal of restoring function. The initial surgery improved the extension contractures of the fingers and wrist substantially, and provided wound coverage. Interestingly, the full-thickness skin grafts took completely on a recipient bed known to be composed of residual tumor. Another case, that of a multicentric variant with extensive upper extremity involvement, has been reported in which split-thickness skin grafting failed. 11 In our patient, the thin skin coverage facilitated tumor surveillance, with residual nodularity and new nodules definitely palpable during the first 2 years after the initial surgery.

When surgery for the more locally aggressive type of solitary infantile myofibromatosis is contemplated, total resection should be avoided in the interest of preserving vital structures. Our patient’s second procedure was performed when she was 5 years old, when we were reasonably certain that the tumor had regressed and when she could comply with postoperative hand therapy.

Infantile myofibromatosis usually presents in neonates. The lesions are most often firm, nonulcerated skin nodules, although locally aggressive solitary lesions with ulceration, as in our patient, have been reported. 11 Appropriate management of this disease is predicated on making the correct diagnosis initially with the help of a skilled pathologist, and on understanding the lesion’s probable natural history.

Age at onset, site of involvement, and specific histological and ultrastructural features generally suffice to establish the correct diagnosis. Specific management issues are seldom discussed in the available published literature. However, a knowledge of the natural history of these lesions together with the specific complications caused by the fibrosing lesion will help one arrive at a treatment strategy. Based on our experience with this case of a solitary aggressive cutaneous lesion, it seems that incomplete resection to resolve the fibrosing complications is permissible, and additional thin skin grafting allowed lesion surveillance. Definitive treatment of the complications of the condition was possible once lesion regression had occurred. By the same token, one may assume that it is possible to intervene too soon surgically in the natural course of the disease when aggressive growth may be continuing. This might explain the initial skin graft loss in a previously published case report of an extremity lesion, and yet there was later successful reconstruction with tissue expansion. 11

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