Overview

Nodular fasciitis

Nodular fasciitis (also known as pseudo-sarcomatous fasciitis, proliferative fasciitis, or infiltrative fasciitis) is a rapidly growing, noncancerous tumour that forms in the fascia (a layer of connective tissue which surrounds all organs, blood vessels, bones, nerve fibres, and muscles).¹ Their morphology resembles a range of soft tissue tumours, including spindle cell sarcomas, fibromatosis, fibrous histiocytoma, benign nerve sheath tumours, and pleomorphic adenoma, which form lumps or nodules on the skin surface and could be further distinguished using MRI or ultrasound by carrying out a core needle biopsy.² Patient cases for NF are often misdiagnosed because of similar morphologies to other lumps or nodules forming on skin surfaces, and hence NF only represent 0.025% of all tumour cases.³ Commonly found in the upper body, these tumours most commonly form between 20-40 years of age, but the pathological reason behind this is still unclear, but could be a cause of inflammation or trauma.⁴ It is not inherited or associated with genetic predisposition.⁵

Understanding the subtle differences between nodular fasciitis and other soft tissue tumours is crucial for accurate diagnosis and patient care. In this article, we will discuss the key differences between nodular fasciitis and other soft tissue tumours, how they are diagnosed, and their clinical analysis. This will also help in understanding the importance of precision medicine, which guides patient management.⁶

Soft tissues

Soft tissue tumours could be malignant or benign. Benign tumours are abnormal, noncancerous cells which do not invade surrounding tissues and are limited to a specific region in the body due to compartmentalisation. Malignant tumours, however, are abnormal cancerous cells which spread to different regions of the body despite cell membrane barriers through the blood or lymphatic system, by a process known as metastasis.⁷ Most soft tissues are malignant tumours, however, NF (despite being a soft tissue) is benign and rapidly growing.⁸

It is important to differentiate between the two tumours for an accurate diagnosis and treatment planning. Benign tumours like NF may require monitoring or surgical removal if symptomatic or causing functional impairment. In contrast, malignant soft tissue tumours necessitate more aggressive treatment approaches such as surgery, radiation therapy, or chemotherapy to target both the primary tumour and any metastatic spread.⁹ The characteristics of both tumours can enable healthcare professionals to provide appropriate management strategies tailored to each patient's specific condition and prognosis. Early detection, accurate diagnosis, and personalised treatment plans are essential in optimising outcomes and quality of life for individuals affected by these tumours.¹⁰

Differentiating tumours

Microscopic analysis

Microscopic imaging studies and histopathological analyses

Nodular Fasciitis (NF) is characterised by Spindle-shaped myofibroblastic cells arranged in a storiform pattern, while malignant tumours have irregular pleomorphic shapes arranged in discoidal, segmental, and spherical patterns. NFs have a myxoid stroma background, along with erythrocytes and scattered lymphocytes.⁸ However, malignant soft tissue tumours have cellular atypia with necrotic cells (dead tissue), haemorrhage (bleeding), and fibrosis (excessive tissue repair).¹¹

NF is classified into 3 subtypes based on fascia interaction:¹²

• Subcutaneous (most frequent subtype seen)
• Intramuscular
• Fascial

Malignant tumours have different 3 main subtypes, which classified according to the anatomical location of the tumour relative to the fascia:¹³

• Superficial Soft Tissue Sarcomas
• Deep Soft Tissue Sarcomas (most common)
• Subfascial Soft Tissue Sarcomas

Molecular and physical diagnosis

Molecularly, NF display specific genetic markers such as MYH9-USP6 gene fusion, resulting in hallmark genetic alteration in nodular fasciitis, not present in other soft tissue tumours. Molecular techniques such as fluorescence in situ hybridisation (FISH) or reverse transcription polymerase chain reaction (RT-PCR) can be used by pathologists to diagnose nodular fasciitis after histological features are inconclusive.¹⁴

Morphological and clinical presentation

The clinical physical presentation of soft tissue tumours varies significantly between NF and other soft tissue tumours because of their being benign and malignant, respectively. NF tumours grow rapidly, forming solitary, firm nodules with painful and tender symptoms, but will often recover with minimal intervention or surgery in other cases. Malignant soft tissue tumours, however, increase in size and are painful too, but require prolonged treatments and medicines. They aggressively invade other surrounding tissues and cause systemic symptoms such as weight loss, fatigue, and possible hair loss.¹⁵

Misdiagnosis

Accurate diagnosis is crucial to avoid overtreating patients and to aid patient outcomes. Misdiagnosing a benign condition like nodular fasciitis as a malignant tumour can lead to significant risks and side effects due to the unnecessary treatments, aggressive surgeries and chemotherapy required to treat malignant tumours. Correct diagnosis of soft tissue tumours must be carried out with conservative management, minimising patient risk and preserving the quality of life. Research showed patient cases of overdiagnosis led to severe physical, emotional, and financial burdens on patients.¹⁶

Summary

Understanding the differences between nodular fasciitis (NF) and other soft tissue tumours is paramount for achieving accurate diagnoses and delivering appropriate treatment to patients. NF, characterised by its rapid growth and benign nature, contrasts with malignant soft tissue tumours in clinical presentation and behaviour. Correctly identifying NF prevents unnecessary invasive procedures, such as surgeries and chemotherapy, which carry risks and can lead to significant stress for patients. By raising awareness among healthcare professionals and educating them on these subtle but crucial differences, we can enhance diagnostic accuracy, minimise the risk of misdiagnosis and overdiagnosis, and ensure that patients receive tailored, effective care. This approach not only improves patient outcomes by avoiding unnecessary treatments but also reduces healthcare costs and preserves quality of life.

FAQs

What are the potential causes of nodular fasciitis?

• Fascial tissue reactive processes
• Potentially triggered by inflammation.
• Proliferation of fibroblasts and myofibroblasts
• Non-inherited

What are the recommended treatment approaches?

• Observing spontaneous regression
• Surgery
• Histopathological examination

What are the risks of recurrence?

• Less than 5% of cases after complete surgical excision.
• Only occurs due to misdiagnosis or incomplete surgery
• Patient follow-ups

What are the consequences of misdiagnosis?

• Extensive surgery or chemotherapy.
• Emotional anxiety
• Financial costs

What is the prevalence compared to malignant soft tissue tumours?

• Nodular fasciitis is rare, accounting for less than 1% of benign soft tissue masses
• Malignant soft tissue tumours (e.g. sarcomas), are more prevalent and pose a higher risk

Read on

If you found this article engaging and informative, we encourage you to explore more articles on Klarity related to Tissue Biology and Oncology. Our extensive collection of well-researched articles provides valuable insights into various aspects of physical and mental well-being.

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• What Is Soft Tissue Sarcoma
• AI In Oncology: Personalised Cancer Treatment Plans
• Skin Cancer FAQS
• What is Nodular Fasciitis?

Note: this article is not designed to replace medical advice: if you are concerned about any symptoms, you must consult your doctor.

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