Dermatology

Nodular fasciitis (subcutaneous pseudosarcomatous fibromatosis, infiltrative fasciitis)

Nodular fasciitis [subcutaneous pseudosarcomatous fibromatosis, infiltrative fasciitis] (ICD-9 728.79, ICD-10 M72.4)

Are You Confident of the Diagnosis?

What you should be alert for in the history

The clinical history of nodular fasciitis consists of a small, superfically located, rapidly growing nodule with a short duration of symptoms from 1-12 weeks. Longer durations of up to a year have also been reported.

Usually patients complain of a single nodule, most frequently found on the upper extremity. Rarely, patients will present with multiple nodules either all at once or at different points in time. Although the tumor is less common in children, lesions in the head and neck are the most frequently occurring variety in patients in this population.

Patients will sometimes complain of pain or tenderness at the sight. Numbness or paresthesia is uncommon and may only occur when the nodule is compressing a peripheral nerve. Ten to 15 percent of cases are associated with a history of trauma.

Characteristic findings on physical examination

On physical examination, the nodule appears well circumscribed, often round or oval in shape, and is thought to lie in the subcutaneous tissue. The size is small, ranging from 0.5-5 cm with an average of 1.5-2 cm. Rare cases of larger lesions measuring up to 10 cm have been documented. It is usually freely moveable without attachment to the overlying skin. Nodules are located most commonly on the upper extremity, specifically the volar aspect of the forearm, with other common places being the trunk, head and neck, and lower extremities. Rare sites include the hand and foot. The intradermal variant can present with additional physical features of superficial ulceration and bleeding and they are often associated with increased amounts of pain.

Expected results of diagnostic studies

Gross Findings

On excisional biopsy the gross appearance of nodular fasciitis depends on the cellularity, matrix composition, and location of the nodule. The lesions can be firm, solid, nodular, or rubbery, and are gray, white or yellow in color. Those lesions with an increased myxoid stroma have a soft and gelatinous consistency whereas those with pronounced collagenous stroma are more firm.

There are three main subtypes of NF; subcutaneous, intramuscular, and fascial. Other less common subtypes include dermal, intravascular, cranial, and ossifying. Most lesions are subcutaneous, well circumscribed, non-encapsulated, and less than 2 cm in diameter. The intramuscular lesions tend to be larger, poorly circumscribed, and invade surrounding soft tissue.

Histopathology

Nodular fasciitis was first described in 1955 by Kornwaler and is a benign proliferation of fibroblasts. This section will emphasize the histological features present most commonly in NF.

Lesions are composed predominantly of fibroblasts, either plump or spindle-shaped, and resemble granulation tissue. The cells vary little in size and shape and have large, pale-staining nuclei with prominent nucleoli. Mitotic figures are common but atypical mitoses are never seen. The fibroblasts are arranged in short bundles or fascicles in a mutually parallel configuration forming an “S” shaped pattern because of the curved cytoplasmic processes. They are accompanied by a dense reticulin meshwork and small amounts of collagen. The bundles are scattered within a rich myxoid matrix, which is responsible for the characteristic loosely textured, “feathery” pattern of NF. More cellular forms have only small amounts of interstitial myxoid material

Many authors point out the importance of clefts between individual fibroblasts, throughout which there are extravasated red cells. Variable numbers of inflammatory cells may also be present, mainly lymphocytes or plasma cells. Although some authors disagree with the notion that there is a relationship between the microscopic picture and the preoperative duration of the lesion, many have found there to be a close correlation.

Early in the course of the lesion myxoid histology is especially prominent. It becomes more cellular with time, and older lesions tend to have a fibrous histology that may be characterized by hyaline fibrosis. Microcysts may also form in lesions of longer duration.

The probing border areas project into and dissect fascial planes and muscle bundles. Proliferating endothelial cells forming small vessels may be found around the periphery of the lesion in a radiating pattern. Multinucleated giant cells and, rarely, osteoid, bone, and cartilage formation, and areas of hemorrhage are additional features encountered.

Cytology

Accurate cytologic diagnosis of nodular fasciitis is possible with knowledge of the fine needle aspiration cytology (FNAC) features along with clinical correlation, thus avoiding unnecessary surgical intervention. Sampling error is a possible limitation of this diagnostic technique. There are three different cytological categories for NF: typical, granuloma-like, and myxoid-like.

Typical NF cytologic features include increased cellularity, isolated cells mixed with tissue fragments and polymorphic patterns that include the following:

Fibroblasts

-Larger than normal

-Spindle shaped

-Lightly basophilic; well demarcated cytoplasm

-Occasional long cytoplasmic processes

-One to two differently shaped nuclei

-Evenly distributed chromatin

-increased mitotic figures

-No atypical mitoses

Giant ganglion cell-like cells

-Greater than twice the size of the fibroblasts

-Enlarged nuclei and nucleoli

Multinucleated giant cells

Tissue culture-like fragments

Few polymorphs/lymphocytes

Granuloma-like NF cytologic features include an Increased number of multinucleated giant cells, hypercellularity, and few or no ganglion cell-like cells.

Myxoid-like NF cytologic features include abundant myxoid material, low cellularity of stromal cells, and no ganglion cell-like cells.

Genetics

-3q21 rearrangements - t(3;15)(q21;q22)

-Chromosomes 15 and 16 rearrangements

Imaging

The appearance on imaging is varied and is based on the histologic composition of the nodular lesions.

Magnetic Resonance Imaging (MRI)

Myxoid/hypercellular composition

-Hyperintense/isointense to skeletal muscle on T1

-Hyperintense to fat on T2

Fibrous/collagenous composition

-Hypointense on all MR imaging

Computed Tomographic (CT) Scan

Myxoid/hypercellular composition

-Lesions are ill-defined with low tissue attenuation

Fibrous/collagenous composition

-Lesions are well-delineated with tissue attenuation approximating that of soft tissue

Staining

Vimentin + (VIM+)

Smooth Muscle Actin + (SMA+)

Muscle Specific Actin +

CD68 + (KP1+)

Desmin - (DES-)

Diagnosis confirmation

Nodular fasciitis is a benign self-limited lesion that is often surgically excised for diagnosis with subsequent complete resolution. Studies using FNAC for diagnosis of NF have shown that the natural history of the lesions may in fact be one of spontaneous resolution.

Nodular fasciitis is the most common benign mesenchymal lesion misdiagnosed as a sarcoma. The differentiation is based primarily on growth pattern and cellularity. In comparison to NF, sarcomas tend to have a longer duration, larger size, usually greater than 4 cm, frequent cellular pleomorphism, increased mitotic rate with atypical mitotic figures, and course, granular chromatin. Cells are almost always densely packed and arranged in interweaving bundles resulting in the characteristic “herringbone” pattern. On MRI, sarcomas can have perilesional tissue edema or intralesional hemosiderin deposition.

Cellular nodular fasciitis may be confused with fibrous histiocytoma (FH). Differentiating features include the fact that FH is dermal-based less well circumscribed, demonstrates more polymorphous proliferation of spindle-shaped and round cells, and has a more consistent storiform pattern. Important secondary elements include the presence of chronic inflammatory cells, siderophages, foamy histiocytes, and the absence of ganglion cell-like cells on cytologic examination. Short duration of the lesion with spontaneous resolution points more towards a diagnosis of NF.

NF lesions with prominent myxoid stroma may be differentiated from a myxoma by the latter’s paucity of cells and poor vascularization Fibromatosis is also in the differential diagnosis but can be grossly differentiated from NF by the large size, usually greater than 3 cm, poorly circumscribed lesion, and the typical invasion of the surrounding soft tissue. Microscopically, fibromatosis is comprised of slender, linear fascicles of cells separated by abundant collagen. Mitotic figures are less commonly seen than in NF.

Both proliferative fasciitis (PF) and proliferative myositis (PM), two other pseudosarcomatous lesions, are considered in the differential of nodular fascitiis. PF is distinguished by the decreased cellularity, increased collagen fragments, and abundance of ganglion cell-like cells on histology. Ganglion cell-like cells are seldom seen on histologic sections of NF but are commonly found in PF, PM and NF with FNAC (fine needle aspiration cytology). Histologically, PM also has ganglion cell-like cells but growth of lesional cells between patches of intact muscle cells with sparing of muscle fibers distinguishes PM from NF. In NF, muscle fibers are obliterated or damaged when the lesions involve the muscle.

The differential diagnosis based on radiologic findings, lesions involving the head and neck, or intradermal lesions are broad.

Radiologic:

-Extraabdominal desmoid tumor

-Neurofibroma

-Fibrous histioctyoma

-Soft-tissue sarcoma

-Myositis ossificans (intramuscular nodules)

Head and Neck:

-Neurogenic tumors

-Minor salivary gland tumors

-Soft tissue tumors (desmoids, epidermoids, hemangiomas)

-Fibrotic tumors (fibrosarcoma)

Intradermal

-Myofibroma

-Fibrous histiocytoma

-Leiomyoma

-Superficial angiomyxoma

Who is at Risk for Developing this Disease?

Nodular fasciitis occurs with a peak incidence in the third and fourth decades, but an age range from infancy to the elderly is reported. There is no male or female predominance and no known associated risk factors.

What is the Cause of the Disease?

Etiology

Pathophysiology

The cause and pathophysiology of nodular fasciitis are unknown. Ten to 15 percent of cases are associated with trauma but trauma alone cannot account for the development of the lesion. Clonal chromosomal aberrations have been reported in a small number of cases. At this point there is no definitive evidence stating whether NF is a reactive or a self-limiting, neoplastic process.

Systemic Implications and Complications

There are no known systemic disorders associated with nodular fasciitis.

Treatment Options

Treatment options for nodular fasciititis are summarized in Table I.

Table I.

Treatment options for nodular fasciitis
Observation alone
Medical
Local – Intralesional corticosteroids
Surgical Excisional biopsy
Physical Modalities None

Optimal Therapeutic Approach for this Disease

Nodular fasciitis is a benign self-limited lesion that is often surgically excised for diagnosis with subsequent complete resolution. Studies using FNAC for diagnosis of NF have shown that the natural history of the lesions may in fact be one of spontaneous resolution.

Excisional Biopsy

Excisional biopsy results in immediate complete resolution of the lesion. In some cases, complete resolution is seen even after partial excision. Bleeding is the only potential risk with excisional biopsy.

Observation

Several studies have shown that an accurate diagnosis of nodular fasciitis can be made with a good clinical history and ctyology from FNAC. These studies have demonstrated spontaneous resolution of NF with a median period of 2 weeks and up to 16 weeks following FNAC. When there is an atypical clinical course, long duration of symptoms, lack of resolution within 4 weeks of diagnosis, or irregular cytologic results with FNAC, excisional biopsy is necessary to rule out other diseases.

The risk of incorrect diagnosis and the existence of a potentially more life-threatening lesion may encourage excisional biopsy over observation alone as the diagnostic and therapeutic modality. While FNAC-based diagnosis is quite recent, histologic diagnosis of NF has been the mainstay since it was first reported.

Intralesional Corticosteroids

One case report of a 5-cm, ill-defined, subcutaneous nodule located on the volar aspect of the right forearm of a 37-year-old female was biopsied for diagnosis. Complete excision of the nodule was too difficult based on its size and infiltration into surrounding soft tissue. Conservative therapy with intralesional injection of corticosteroids demonstrated complete resolution of the lesion within 36 hours of follow-up. Other case studies have also shown regression and eventual resolution with the use of intralesional corticosteroid injections.

Patient Management

The recurrence rate for nodular fasciitis is 1-2%. Recurrence is more common in the pediatric population with lesions in the head and neck region. Patients with excisional biopsy with complete resolution and no recurrence require no further follow-up. Patients with excisional biopsy and incomplete resolution should follow-up for observation or, if there is clinical concern, a wider re-excision. Patients with diagnostic FNAC and observation as their choice of treatment can follow-up with their doctor if the lesion has not resolved within 4 weeks of the diagnosis, if it continues to grow, or if it causes increased amount of discomfort. It is possible that the lesion can take longer than 4 weeks to regress.

Unusual Clinical Scenarios to Consider in Patient Management

Seven to 10 percent of lesions are located in the head and neck. Most cases show a benign nature with complete resolution after excisional biopsy. However, one study included a nodule in the prevertebral space of a 2 year-old boy that demonstrated aggressive behavior with jugular fossa destruction, intracranial extension, and related symptoms, including multiple lower cranial nerve palsies. The study did not clarify if wide excisional biopsy was performed and it did not provide information regarding follow-up of this patient.

Given the benign, self-limited nature of the lesion, it is possible that once the diagnosis of nodular fasciitis is made, no further surgical intervention is necessary and it can be observed for regression. In the case of an aggressive lesion, an alternative could be to do a trial of intralesional corticosteroid injections, which demonstrated complete regression of the lesion within 36 hours in one case study.

What is the Evidence?

Dinauer, PA, Brixey, JC, Moncur, JT, Fanburg-Smith, JC, Murphey, MD. "Pathologic and MR imaging features of benign fibrous soft-tissue tumors in adults". Radiographics . vol. 27. 2007. pp. 173-87.

(The benign fibrous soft tissue tumors that most often occur in adults are discussed, with emphasis on common anatomic sites of manifestation, MR imaging features, and corresponding pathologic findings. The article describes the general signal intensity of soft tissue tumors based on histologic composition, stating that hypocellular fibrous tumors with dense collagenous components tend to have lower signal intensity on T2-weighted images than do lesions that have increased cellularity and contain a rich extracellular myxoid matrix. A differential diagnosis based on MR imaging results is also provided.)

Shin, JH, Lee, HK, Cho, KJ, Han, MH, Na, DG, Choi, CG, Suh, DC. "Nodular fasciitis of the head and neck Radiographic findings". J Clinical Imag . vol. 27. 2003. pp. 31-7.

(A retrospective study of the clinical and radiological findings of six patients with proven nodular fasciitis of the head and neck region. The diagnosis of nodular fasciitis was based on histologic data. The population consisted of four males and two females, ages 2-52. The study included a total of seven radiologic examinations; four CT, two US, and one MR. The images were evaluated based on several criteria including lesion size, lesion location, density on CT, signal intensity on MR, and the heterogeneity and degree of enhancement on CT and MR and others. There were three subcutaneous and three intramuscular lesions in the study and one intramuscular lesion destroyed the skull base including the jugular fossa and involved the intracranial meninges with preservation of the brain parenchyma. This aggressive nature is of note because most cases show a benign course. The study found variable signal intensities on MR, strong enhancement on CT, and mixed signals on US. The study made little correlation between the histologic appearance of the lesions and imaging results which has been described as the main determinant of imaging results in previous articles.)

Allen, PW. "Nodular fasciitis". Pathology . vol. 4. 1972. pp. 9-26.

(This paper is a review of 895 cases of nodular fasciitis that were compiled at the Armed Forces Institute of Pathology (AFIP) from 1957 to 1970. It provides updated information from previously published reports by the AFIP with particular attention to 96 consecutive cases seen from May 1969 to June 1970. It delineates the four most common histological features of nodular fasciitis as well as those less constant. The paper goes into detail about clinical history, gross pathology, histopathology, differential diagnosis, prognosis, and treatment. It concludes with a detailed review of 9 recurrent lesions [~1%.]).

Shimizu, S, Hashimoto, H, Enjoji, M. "Nodular fasciitis: Analysis of 250 patients". Pathology . vol. 16. 1984. pp. 161-66.

(This article is a summary analysis of 250 cases from 1956 to 1981 registered as soft tissue tumors at the Second Department of Pathology at Kyushu University in Japan. Results of anatomical location, gross appearance, histology, and clinicopathological correlations were discussed. Follow-up data was available for 56% of patients with recurrence documented in one patient. Regarding the histology, Shimizu et al modified previous classifications proposed by other studies and subdivided nodular fasciitis into three types; myxoid, cellular, and fibrous. They found a correlation age of the lesion and a progression from a myxoid to cellular and finally fibrous composition.)

Wong, NL, Di, F. "Pseudosarcomatous fasciitis and myositis, Diagnosis by fine-needle aspiration cytology". Am J Clin Pathol . vol. 132. 2009. pp. 857-65.

(A follow-up study of 52 cases of pseudosarcomatous lesions demonstrating the ability to accurately diagnose these lesions with fine needle aspiration cytology. A previous study by the same group of 17 cases determined that it was possible to differentiate pseudosarcomatous reactive proliferative soft tissue lesions from true sarcoma based on cytologic criteria in FNAC along with clinical correlation. The larger study included 46 cases of nodular fasciitis, three cases of proliferative fasciitis, and two cases of proliferative myositis. All of the cases of NF were recent-onset, small superficially located, rapidly growing nodules. Most cases of NF demonstrated typical cytologic features with a minority demonstrating granuloma-like or myxoid features. In conclusion, the study determined that lesions can be diagnosed by FNAC and they should be managed nonsurgically initially, with follow-up at 4 weeks. Excisional biopsy should be reserved for cases that do not regress within 4 weeks of diagnosis, have an atypical clinical course, or do not demonstrate a known cytological appearance of NF.)

Graham, BS, Barett, TL, Goltz, RW. "Nodular fasciitis: response to intralesional corticosteroids". J Am Acad Dermatol . vol. 40. 1999. pp. 490-92.

(A case report describing a 34-year-old healthy black female who presented with a 9-day history of a rapidly growing painful subcutaneous nodule on the volar aspect of her right forearm with intermittent ulnar nerve paresthesias. Further examination revealed a 5-cm subcutaneous nodule fixed to underlying tissue, diffusely dissecting within the fascia and between muscle bundles with free mobile overlying skin. The lesion continued to grow rapidly and the patient requested an aggressive surgical intervention. Based on the size and infiltrating borders, a large surgical excision would have been necessary. Instead, intralesional injection with triamcinolone acetonide was attempted and resulted in complete resolution at 36-hour follow-up. The case report demonstrated that for large or deep lesions, where surgical excision could result in significant morbidity, a trial of intralesional corticosteroids after the initial diagnostic biopsy should be considered.)

Donner, LR, Silvia, T, Dobin, SM. "Clonal rearrangement of 15p11.2, -16p11.2, and 16p13.3 in a case of nodular fasciitis: additional evidence favoring nodular fasciitis as a benign neoplasm and not a reactive tumefaction". Cancer genet cytogenet . vol. 139. 2002. pp. 138-40.

(A case report of nodular fasciitis in a 48-year-old white man who presented with a mass on his right hypothenar that occurred after falling from a horse. The lesion was initially rapidly growing but had remained stable for a month. Pathologic features were consistent with nodular fasciitis and cytogenetic analysis was also performed. This case found two cells from an explant culture with the karyotype 46,XY, add(15)(p11.2),t(16;16)(p13.3;p11.2) and three cells, one derived from an explant and two from collagenase-treated cells, with trisomy 4. A nonclonal translocation of 3q21 and 5q was also found. The authors of this case study point to the fact that trauma and resulting inflammatory and repair processes are known to act as promoters of tumorigenesis. They also state that the presence of clonal chromosomal abnormalities, in contrast to the presence of mere numerical chromosomal changes, contradicts a reactive process and is more indicative of preneoplastic or neoplastic processes.)

Nishi, SPE, Brey, NV, Sanchez, RL. "Dermal nodular fasciitis: three case reports of the head and neck and literature review". J Cutan Pathol . vol. 33. 2006. pp. 378-82.

(This case review describes three different dermal lesions in the head and neck. One patient was 15 years old with a lesion on her left cheek while the other two patients were 40 and 39 years-old with lesions at the base of the scalp and on the right medial canthus, respectively. The left cheek nodule was incompletely excised and histologically shown to be NF. At follow-up, the nodule had almost doubled in size, at which point the patient was treated with intralesional steroid injection with reduction in size and eventual resolution of the lesion. The lesion at the base of the scalp required re-excision and complete resolution at 1-year follow-up and the right canthus lesion was originally treated unsuccessfully with doxycycline, diagnosed by incisional biopsy, and had spontaneously regressed on follow-up. The article discusses differences in clinical presentation and a broad differential diagnosis of dermal nodular fasciitis.)

Feraudy, Sd, Fletcher, CDM. "Intradermal nodular fasciitis, a rare lesion analyzed in a series of 24 cases". Am J Surg Pathol . vol. 34. 2010. pp. 1377-81.

(This article describes 24 cases of intradermal nodular fasciitis received between 1990 and 2008. It discusses specific differences in intradermal NF with regards to clinical presentation, location, gross and histologic features, and differential diagnosis. Other reports have stated that dermal NF is most common in the head and neck region whereas this article found in the 24 cases reviewed that the trunk and limbs are more common.)

Enzinger, FM, Weiss, SW. "Soft tissue tumors". Mosby. 1995. pp. 247-300.

(This chapter focuses on benign fibrous tissue tumors such as nodular fasciitis, proliferative fasciitis, and proliferative myositis. It describes the clinical presentation, gross, microscopic, immunhistochemistry, and ultrastructural findings as well as a detailed differential diagnosis. The section on nodular fasciitis also includes an explanation of the less common subtypes including ossifying, intravascular, and cranial fasciitis.)
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