Overview 

Nodular fasciitis is a benign soft tissue tumour that frequently appears as an aggressively developing mass, which can worry patients and medical professionals. Although non-cancerous, its clinical and pathological similarities to malignant soft tissue tumours can make diagnosis difficult. This article aims to examine the common anatomical locations impacted by nodular fasciitis, emphasising the condition's clinical manifestation, methods of diagnosis, and available treatments.

Introduction to Nodular Fasciitis

A benign, reactive growth of myofibroblasts and fibroblasts occurring within the muscle, fascia, or tissue beneath the skin is known as nodular fasciitis. Due to its fast development and sarcoma-like histological traits, it is also known as pseudosarcomatous fasciitis, having been first reported in 1955 by Konwaler et al. Nodular fasciitis is a self-limiting condition that seldom returns following excision, despite its frightening appearance. 

Pathophysiology and aetiology

The cause of nodular fasciitis remains unclear. Though many occurrences occur without any prior damage, it is believed to be the result of a reactive process, potentially initiated by trauma or an inflammatory reaction. A recurring MYH9-USP6 gene fusion has been found in a considerable percentage of patients by recent investigations, indicating a possible genetic foundation for the illness. 

Clinical presentation

Usually, a fast-growing, hard, and occasionally painful lump is seen in patients with nodular fasciitis. The lesion may be a few millimetres to several centimetres in size, and is often well-circumscribed. Though erythema and warmth may occasionally be observed, the skin layer above typically does not exhibit significant changes.

Diagnostic approaches

A multidisciplinary approach involving imaging, histological analysis, and clinical evaluation is required to diagnose nodular fasciitis. In a clinical evaluation, a healthcare professional reviews the individual’s medical history, taking note of the mass's rapid development and associated symptoms, including pain or discomfort. A solid, well-circumscribed lump that may be palpably painful is frequently present during a physical examination.

Imaging is essential to the diagnosis procedure. As ultrasound offers a rapid and non-invasive lesion evaluation, it is frequently the first imaging modality to be employed. Nodular fasciitis usually presents as a well-defined, hypoechoic lump on ultrasonography. On Doppler ultrasonography, the lesion may show enhanced vascularity, indicating its fast development and cellular activity. 

A more thorough assessment of the lesion is provided by magnetic resonance imaging (MRI), particularly with reference to its location and association with surrounding structures. A well-demarcated mass that is usually hyperintense on T2-weighted imaging and isointense to muscle on T1-weighted images is one of the MRI features of nodular fasciitis. Despite the differences in post-contrast enhancement patterns, the lesion's myxoid stroma and cellular components typically result in heterogeneous enhancement. In addition to helping to define the lesion, MRI is useful in ruling out other diagnoses, such as malignant soft tissue tumours.

Common anatomical sites

Nodular fasciitis can occur in any part of the body, though it is most commonly localised in the upper extremities, head and neck region, and trunk. Here, we will discuss the clinical characteristics and implications of nodular fasciitis in these common anatomical sites.

Upper extremities

The upper extremities are the most common site for nodular fasciitis presentation, accounting for approximately 40-50% of cases. Within this region, the forearm is particularly frequently affected.

Clinical presentation

• Patients typically present with a firm, rapidly growing mass in the subcutaneous tissues of the forearm or arm
• Pain and tenderness may be present, especially if the lesion is compressing nearby nerves or other structures
• The overlying skin usually appears normal, although erythema and warmth can occur in some cases

Diagnostic challenges

Nodular fasciitis in the head and neck region often presents as a painless or mildly tender lump located within the subcutaneous tissue of the face, parotid area, or scalp. These lesions are typically firm, well-defined, and noted for their rapid growth, a feature that, despite their benign nature, can cause significant concern for patients. The sudden appearance and enlargement of the mass frequently prompt urgent medical evaluation. Although the overlying skin generally remains unaffected, signs of inflammation such as erythema or localised warmth may occasionally be present.

Treatment

The location of nodular fasciitis lesions in the head and neck can pose unique challenges due to the dense concentration of critical anatomical structures. Lesions near the facial nerve may impact facial expressions, while those close to the salivary glands can disrupt saliva production and flow. Scalp involvement may lead to prominent swellings, which can be both aesthetically concerning and psychologically distressing. Because of their rapid progression and proximity to vital structures, these lesions necessitate careful clinical assessment and imaging to determine their effects and guide appropriate management. Treatment aims to alleviate any functional deficits and address cosmetic concerns, ensuring both medical and psychological well-being.

Head and Neck region

Nodular fasciitis in the head and neck region accounts for approximately 20% of cases. Within this area, it most commonly affects the parotid gland, cheek, and scalp.

Clinical presentation

Patients may present with a painless or slightly tender mass located in the subcutaneous tissue of the cheek, parotid region, or scalp. These lesions are typically firm and well-circumscribed, with rapid growth being a characteristic feature.

Due to the proximity of these lesions to vital structures in the head and neck region, they can cause functional impairments or cosmetic concerns. This can include difficulties with facial movement, speech, or swallowing, depending on the exact location and size of the mass.

Diagnostic challenges

The rapid growth and firm consistency of the mass can raise suspicion for malignant tumors such as salivary gland neoplasms or sarcomas. Fine-needle aspiration or core needle biopsy can aid in the diagnosis by providing tissue samples for analysis, though an excisional biopsy may be necessary for a definitive diagnosis to thoroughly evaluate the lesion and rule out malignancy.

Treatment

Complete surgical excision is the preferred treatment for nodular fasciitis, as it effectively removes the lesion with a low risk of recurrence. This approach is typically successful as the likelihood of recurrence is low due to the benign nature of nodular fasciitis. However, the decision to pursue complete excision must consider the lesion's location, especially in areas where surgery might result in significant functional or cosmetic deficits. 

For instance, in the head and neck region, where the mass may be near vital nerves or structures, complete removal could impact facial movement, saliva production, or appearance. In such cases, partial excision or close observation with regular follow-up may be more appropriate. Therefore, treatment plans for nodular fasciitis are tailored to individual cases, considering both the medical and personal implications of surgical intervention.

Trunk

The trunk, including the chest wall, back, and abdominal wall, is another common site for nodular fasciitis, accounting for around 15-20% of cases.

Clinical presentation

• Patients typically present with a firm, rapidly growing mass in the subcutaneous tissue or muscle of the chest wall, back, or abdominal wall
• The lesion may be painful or tender, particularly if it is large or compressing adjacent structures
• The overlying skin usually appears normal, although erythema and warmth can occasionally be present

Diagnostic challenges

• Differentiating nodular fasciitis from other soft tissue tumours, both benign and malignant, is essential
• Imaging studies such as MRI can help characterise the lesion and assess its relationship with surrounding tissue

Treatment

The preferred therapy is surgical excision due to its low chance of recurrence. 

Lower extremities

Nodular fasciitis in the lower extremities, though less common than in the upper extremities, can still occur and pose similar diagnostic and therapeutic challenges.

Clinical presentation

• Individuals typically present with a firm, rapidly growing mass in the subcutaneous tissue of the thigh or lower leg
• Pain and tenderness may be present, especially if the lesion is compressing nearby nerves or other structures
• The overlying skin usually appears normal, although erythema and warmth can occasionally be present

Diagnostic challenges

• Differentiating nodular fasciitis from other soft tissue tumors, both benign and malignant, is crucial
• Imaging studies such as MRI can provide detailed information on the lesion's characteristics and its relationship with adjacent tissues

Treatment

In certain instances, especially when the lesion is minor and asymptomatic, it could be suitable to observe and monitor the condition. 

Intra-abdominal and retroperitoneal

Nodular fasciitis occurring in the intra-abdominal and retroperitoneal regions is rare but noteworthy due to the unique challenges posed by these locations.

Clinical presentation

Individuals with nodular fasciitis in the intra-abdominal or retroperitoneal region often present with a firm, rapidly growing mass, which is frequently discovered incidentally during imaging for other conditions. The lesion may cause pain or discomfort, especially if it becomes large or compresses adjacent structures. Due to its deep location, the overlying skin generally appears normal.

Diagnostic challenges

Differentiating nodular fasciitis from other intra-abdominal or retroperitoneal masses, including malignant tumors, is crucial. Imaging studies, such as CT or MRI, are instrumental in characterising the lesion and evaluating its relationship with surrounding tissues. For a definitive diagnosis, a biopsy may be necessary to provide conclusive histopathological evidence.

Treatment

• Surgical excision is the treatment of choice, with a low risk of recurrence
• In some cases, particularly if the lesion is small and asymptomatic, observation and follow-up may be appropriate

Summary

Nodular fasciitis is a benign, rapidly growing soft tissue tumour, most commonly present in the upper extremities, head, neck, and trunk. Due to its similarity to malignant tumours, accurate diagnosis is vital. Clinical evaluation, imaging, and histopathology are essential for proper identification, with surgical excision being the primary treatment.