Fasciitis

Nodular fasciitis (Nodular fasciitis)

This is a benign reactive lesion of the fascial tissue.

MRI diagnostics directly depends on the stage of the process:

• Early stage: the lesion is dominated by myxoid tissue. Signal intensity on tomograms is close to fluid (mild hyperintensity is observed on T1-weighted images compared to surrounding muscles).
• Late stage: the lesion gradually undergoes fibrosis. Due to dense connective tissue, it becomes hypointense (dark) on all MRI sequences, including T1.

Management: a biopsy is mandatory to confirm the diagnosis. Treatment includes intralesional corticosteroid injection and surgical intervention. After proper excision, recurrences are extremely rare.

Role of fasciae and compartment syndrome

Limb muscles are surrounded by bands of dense connective tissue—fascia (fascia). The space within it is called a fascial compartment (compartment). For example, the leg has four such compartments: anterior, lateral, deep posterior, and superficial posterior.

If pressure rises within this enclosed space, acute compartment syndrome (Acute Compartment Syndrome) develops.

Causes:

• Trauma (especially tibial fractures).
• Tight casting or bandages (tight casts).
• Reperfusion injury following vascular surgery (reperfusion injury).
• Tissue infiltration during intravenous infusions.

Pathogenesis and clinical features: increased pressure disrupts blood flow, reduces perfusion, and causes hypoxia. The leading symptom is progressive pain caused by the accumulation of lactate (a product of anaerobic metabolism).

Treatment: emergency fasciotomy (urgent fasciotomy) — incision of the fascia to decompress the affected compartment and save nerves and muscles.

Fascial defects: muscle hernia

Sometimes the fascia can rupture completely while the muscle itself is partially preserved. This leads to the protrusion of muscle tissue through the defect, forming a muscle hernia. Most commonly, this pathology occurs on the outer surface of the thigh and leg.

Clinical picture:

• An elastic, tumor-like mass is palpable.
• The 'hernial ring' in the fascia can be felt at the border of the protrusion.
• Specific sign: the hernia decreases when the muscle contracts and increases when it relaxes.

Usually, the condition does not affect limb function and requires no special treatment. Surgical repair of the fascial defect is indicated only for persistent pain (due to aseptic inflammation at the ring) or for cosmetic reasons.

Fibromatoses: systemic fascial lesions

Fibromatoses are a group of diseases characterized by local proliferation of mature fibroblasts and collagen bands in fasciae and aponeuroses.

1. Palmar fibromatosis (Dupuytren's disease): thickening of the palmar fascia with the formation of cords. Leads to disabling flexion contracture of the 4th and 5th fingers of the hand.
2. Plantar fibromatosis (Ledderhose disease): involvement of the medial margin of the plantar fascia. Unlike the palmar form, flexion contractures are practically absent here.
3. Penile fibromatosis (Peyronie's disease): induration on the dorsolateral surface, causing penile curvature.
4. Desmoid-type fibromatosis: deep, locally aggressive clonal proliferation. On MRI, it has a specific feature—low-signal tissue bands (dense collagen bundles). When superficially located, it is palpable as a very dense mass, which can complicate needle biopsy.

Elastofibroma: chest wall pseudotumor

Elastofibroma (Elastofibroma) is a tumor-like lesion consisting of mature adipose tissue enclosed in a fibrous mass.

Developmental features:

• Occurs almost exclusively in elderly patients (detected in 2% of individuals over 60 years old on chest CT).
• Considered the result of constant friction between the scapula and the chest wall (e.g., due to heavy physical labor), leading to collagen degeneration.
• More than 50% of cases are asymptomatic and represent an incidental finding.

Diagnosis and treatment: typical localization is below the inferior angle of the scapula, deep to the serratus anterior muscle. CT and MRI typically show alternating bands of fatty (bright on T1) and fibrous (dark) tissue. With a typical presentation, biopsy is not required, and marginal resection (marginal resection) is sufficient for treatment.

Class and exam questions

What else to study on this topic

• Anatomy of the fascial compartments of the leg: muscles, vessels, and innervation
• Acute compartment syndrome: pathogenesis, diagnostics, and fasciotomy technique
• Dupuytren's disease and Ledderhose disease: conservative and surgical treatment
• Desmoid fibromatosis: growth features and differential diagnosis
• Heterotopic ossification (myositis ossificans): causes and morphology

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.