Stiff skin syndrome

Overview

Stiff skin syndrome (SSS) is a rare connective tissue disorder characterized by progressive thickening, hardening, and induration of the skin, primarily affecting children. Unlike scleroderma, SSS does not typically involve internal organs or cause systemic fibrosis. The condition leads to restricted joint mobility due to skin tightness and may result in functional impairment. It is classified as a form of cutaneous fibromatosis with a distinct clinical and histopathological profile.

SSS is a lifelong condition that often presents in early childhood and requires multidisciplinary management to preserve mobility and quality of life.

Causes

Stiff skin syndrome is caused by mutations in the FBN1 gene, which encodes fibrillin-1, an essential glycoprotein involved in the formation of elastic fibers in connective tissue. These mutations lead to abnormal extracellular matrix deposition and excessive fibrosis of the skin. The disorder is inherited in an autosomal dominant pattern, though some cases may arise from spontaneous mutations.

The genetic defect disrupts the normal architecture and elasticity of the skin, causing progressive stiffness and thickening.

Symptoms

The hallmark symptoms of stiff skin syndrome include:

• Progressive skin thickening and induration, particularly over the trunk, abdomen, and proximal limbs

• Firm, woody texture of the affected skin

• Restricted joint mobility due to skin tightness, leading to flexion contractures

• Normal systemic examination with absence of internal organ fibrosis

• Normal or mildly delayed growth in some patients

• Possible mild musculoskeletal discomfort or stiffness

Unlike systemic sclerosis, patients with SSS do not typically exhibit Raynaud's phenomenon, nailfold capillary changes, or visceral involvement.

Diagnosis

Diagnosis of stiff skin syndrome is based on clinical findings, histopathology, and genetic testing:

• Clinical evaluation: Identification of characteristic skin changes and joint contractures without systemic features.

• Skin biopsy: Reveals thickened collagen bundles in the dermis with increased fibroblast activity and reduced elastic fibers.

• Genetic testing: Detection of pathogenic mutations in the FBN1 gene confirms diagnosis.

• Laboratory studies: Generally normal; autoimmune markers are absent, helping to differentiate from scleroderma.

• Imaging: May be used to assess joint contractures and exclude internal organ involvement.

Treatment

There is no cure for stiff skin syndrome, so treatment focuses on symptom management and maintaining function:

• Physical and occupational therapy: Essential to maintain joint mobility, prevent contractures, and improve daily functioning.

• Skin care: Moisturizers and protective measures to prevent skin breakdown.

• Surgical intervention: May be considered for severe contractures limiting mobility.

• Medications: Limited evidence supports use of antifibrotic agents; corticosteroids and immunosuppressants are generally ineffective.

• Genetic counseling: Recommended for affected families to discuss inheritance and reproductive options.

Prognosis

Stiff skin syndrome is a chronic condition with a generally stable course. While skin stiffness and joint contractures may progress slowly, the absence of internal organ involvement distinguishes it from systemic sclerosis and contributes to a better overall prognosis.

With early intervention and consistent therapy, many patients can maintain good mobility and quality of life. Regular follow-up is important to monitor joint function and address complications promptly.