Plantar fibroma is a common occurrence in the plantar aponeurosis that usually consists of a solitary lesion or multiple nodules. The condition commonly derives from the medial and central fascial band of the aponeurosis, and is typically non-cancerous. Plantar fibromas are generally slow growing lesions that are typically asymptomatic. Most nodules cause pain because of the irregular contour of the foot with ambulation and standing.
The cause of plantar fibomas cannot typically be determined but trauma to the aponeurosis and, in some cases, patients on phenytoin (Dilantin) can develop lesions. Those with systemic conditions such as epilepsy, alcoholism, liver cirrhosis, hypothyroidism and diabetes mellitus may have an increased incidence of plantar fibromas.
Fibromatoses present through different stages of life. Plantar fibromatoses represent a heterogeneous group of local infiltrative pathology. When it comes to the histological view, plantar fibromatoses have mature collagen and fibroblasts with no malignant cytological features.
Plantar fibromatoses are a group of proliferative soft tissue disorders. They are characterized by an infiltrative pattern of growth with repeated local recurrences and the proliferation of uniform but well differentiated spindled cells (mainly myofibroblasts) and a variable amount of collagen among the proliferating cells. These lesions are locally aggressive but typically lack the capacity to metastasize.
Ledderhose first described plantar fibromatosis as a non-malignant thickening of deep connective tissue or plantar fascia. It is a minor, non-painful tumor commonly referred to as Ledderhose disease. As the disease progresses, it may cause thickening of the cord and contractures of the digits, which, in turn, can cause pain. Men typically get the disease at an earlier age than women. Similar to Dupuytren’s contracture, the incidence of plantar fibromatosis is about even for men and women with the disease being more progressive for men in their 70s.
Plantar fibromatosis, as well as Dupuytren’s contracture, has no clear pathophysiologic factors. However, researchers have reported the occurrence of the disease in patients with repeated trauma, long-term alcohol consumption, chronic liver disease, diabetes and epilepsy. The clearest factor with the disease lies with heredity.
Essential Insights On Differentiating Between Plantar Fibromas
Superficial plantar fibromatosis is more common in the younger population than in the elderly population. Although it is classified as a tumor that shows fibroblastic proliferation and overgrowth, myofibroblast proliferation is common with some forms.
Cerebriform mesodermic hamartomas is a form of plantar fibromatosis that represents a kind of mesodermal nevus when one sees it on the sole of the foot. It is associated with Peyronie’s disease, which is characterized by a plaque or hard lump that forms on the penis. The cause is unknown. The plaque develops on the upper or lower side of the penis in layers containing erectile tissue. It begins as a localized inflammation and can develop into a hardened scar.
One may distinguish desmoid tumors from plantar fibromatosis by the different anatomical site, treatment response and more aggressive pathological characteristics. Desmoid tumors are present in and around the large muscle of the trunk and extremities. In the foot, the desmoid tumor represents a tumor deep in the plantar arch and is not superficial as one would see with plantar fibromatosis. Desmoid tumors are also associated with a rare condition called Gardner syndrome.
According to Montgomery, et al., desmoid tumors and plantar fibromatosis are common in their histomorphologic grounds but differ in production, mass size and activity. These authors found that the APC/b-catenin pathway may play a role in the different growth characteristics of superficial versus deep fibromatosis, and that these two categories of fibromatosis are truly and genetically distinct.
Juvenile aponeurotic fibroma is a rare tumor that presents in patients who are 20 years of age or younger. The fibroma forms a hard, discrete mass on the plantar sole that is amenable to surgical excision with functional preservation.
Aggressive infantile fibromatosis is a rare single or multiple nodule mass that has a rapid growth and occurs within the first year of life. Histologically, it resembles fibrosarcoma. Surgical excision is recommended with local aggression but some may regress with observation.
Other Key Points To Consider During The Clinical Exam
Plantar fibromatosis is a common soft tissue tumor of the foot. As the disease progresses in the elderly population, plantar contracture develops in approximately 25 percent of the patient population. The incidences of superficial plantar fibromatosis and cerebriform mesodermic hamartomas are unknown. Its clinical representation of a plantar fibromatosis is rare.
Typically, the various forms of plantar fibromatosis are asymptomatic. They present as a mass of a solitary lesion or multiple nodules within the medial and or central bands of the plantar aponeurosis. Symptomatic patients have difficulty wearing shoes and the ability to stand or ambulate because of the irregularity of the contour of the plantar arch.
Plantar fibromatosis is typically bilateral. Local infiltrates often recur with just local resection. However, performing a complete plantar fasciotomy will reduce recurrence. Superficial plantar fibromatosis may grow gradually and recur when one excises them. Both aggressive infantile fibromatosis and fibrosarcoma have an infiltrative course but only aggressive infantile fibromatosis does not metastasize.
In regard to plantar fibromatosis, one would see this in the middle-aged to elderly population. Juvenile aponeurotic fibroma is more prominent in younger males than young females. Aggressive infantile fibromatosis and cerebriform mesodermic hamartomas are the only exceptions in that they only occur within the first year of life.
Differentiating Lesions From A Histological Perspective
In regard to plantar fibromatosis, the proliferation of tumor cells grows both superficial and deep from the aponeurosis. It will replace the adipose tissue. However, it will not affect the overlying epidermal and dermal layers.
Superficial plantar fibromatosis’ cellular limits are usually not well defined. Areas of the disease may be similar to fibrosarcoma in which the cellular structures are closely packed together with a dense fibrocytic component. Some areas can be scar-like and acellular. Superficial plantar fibromatosis is commonly located in the posteromedial and plantar portion of the heel. The nodules are usually asymptomatic with round to flattened lesions with a fibrous consistency.
In juvenile aponeurotic fibroma, the cellular structures are oat-shaped. In the aggressive forms, there is an increase in mitotic activity and they are more cellular. The nodular lesions are hard, slow growing and adhere to the deep structures of the foot.
Aggressive infantile fibromatosis appears within the first year of life. The lesion is a fast growing tumor that rapidly infiltrates the subcutaneous fat, aponeurosis and muscle. Its course is similar to fibrosarcoma but metastasis does not occur.
A Guide To Staging Of Soft Tissue Tumors
Classification schemes are based on the radiographic, histological and clinical presentations. Enneking classified benign soft tissue tumors in three stages: latent, active and local aggressive growth. With stage I, the latent stage, the tumors are usually static or inactive and asymptomatic. In Stage II, the active stage, the lesions are actively growing and cause clinical symptoms. In Stage III, the local aggressive growth stage, lesions are locally aggressive, histologically immature and show progressive growth not limited to normal boundaries.
Malignancy is rare in the various forms of plantar fibromatosis. The staging of malignant tumors acts as a baseline for determining prognosis and treatment protocols. Soft tissue sarcomas are based on a number of variables. These variables include: histological grade, tumor size, tumor depth, compartment status and the presence or absence of metastasis.
Enneking staged these different components for surgical intervention. The classification identified the sarcomas as either low grade (Stage I) or high grade (Stage II) sarcomas. The classification also addresses histological appearance and diagnostic imaging, and whether the sarcoma is intra-compartmental or extra-compartmental. The third stage of the Enneking surgical staging system for malignant soft tissue sarcoma is whether the tumor consists of no distant metastasis or any regional or distant metastasis.
What You Should Know About Diagnostic Imaging Of These Lesions
Diagnostic imaging plays an important role in the diagnosis of various forms of plantar fibromatosis. In general, one should take a radiograph to evaluate bony structures. Obviously, the radiograph will not show any soft tissue structure but will show local invasive bone destruction (although this is rare). Ultrasound has become increasingly popular as a diagnostic modality for soft tissue tumors.
Ultrasound will show the local lesion as a hypoechoic mass but fails to show the true extent of the lesion.
Magnetic resonance imaging (MRI) is useful for detecting planar fibromatosis. It will show signal intensity of heterogeneity and infiltrative margins. It also shows the degree of deep invasion of plantar fibromatosis. Magnetic resonance imaging shows that the plantar fibromatosis lesion is not well encapsulated but is well circumscribed. The lesion, with MRI, is typically of low signal in both T1 and T2 weighted images. This is due to its large collagen content. Magnetic resonance imaging short TI inversion recovery (MRI STIR) is helpful in distinguishing more aggressive lesions.
Pertinent Pointers On Treatment Options
Typically, plantar fibromatosis is asymptomatic and treatment for patients with early disease requires observation. Patients who have an early stage lesion should receive a persistent trial of conservative treatment, which should include: padding, orthotic management, non-steroidal antiinflammatory drugs (NSAIDs) and physical therapy. Intralesional injection therapy with corticosteroids has some merit in the initial stages of the disease but as the disease accelerates, its success rate is doubtful.
One should evaluate surgical intervention for the various forms of plantar fibromatosis on a case-by-case basis. In a symptomatic case of plantar fibromatosis not relieved by conservative measures, take a radical excision of the plantar fascia. Take at least 1.5 cm of normal fascial tissue. Large exposure is necessary to uncover the entire lesion. A Z-shaped or an S-shaped surgical incision can give complete exposure to the entire plantar fascia for a radical plantar fasciotomy. When excising the lesion, take care not to disrupt tissue deep to the medial fascial band. Since lesions are commonly limited to the medial fascial band, be careful not to disrupt the medial plantar digital nerve and flexor hallucis brevis muscle. These structures run just deep to the plantar aponeurosis.
Plantar fibromatosis has a high recurrence rate. This rate is decreased with radical excision of the plantar fascia. However, be aware that recurrence is high and usually rapid. If the tumor recurs, the rate of malignancy is quite low.
Desmoid tumors require a radical excision of the lesion. Often adjunct treatment may be required. This may include radiation treatment, estrogen blockage and chemotherapy. Resection of this kind of plantar fibromatosis has an intermediate recurrence rate of 20 percent. Although adjunct therapy will reduce the rate of recurrence, amputation may be required for multiple recurrences. When commencing closure, utilize a drain to reduce the risk of hematoma formation and flap necrosis. Place this patient in a non-weightbearing Jones compressive dressing for at least 21 days. One should use accommodating orthoses after surgical correction.
In regard to the other forms of plantar fibromatosis, especially the infantile forms, surgical correction is limited because of the spontaneity of the lesion to regress. Obtaining a biopsy of the lesion may induce this regression.
Plantar fibromatosis has an increasingly favorable prognosis with complete radical excision of the plantar aponeurosis. One should consider surgery only when palliative measures have failed and the tumor has progressed from its early stages.
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