What is the fibroglass sign of hidradenitis suppurativa (HS)?

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From the Guidelines

The fibroglass sign is a characteristic clinical finding in hidradenitis suppurativa, where a thin, fibrous strand of tissue can be expressed from sinus tracts or lesions, and is considered pathognomonic for the disease. This sign appears when gentle pressure is applied to an active lesion, causing a white, stringy, fibrous material to emerge from the opening, resembling fibreglass insulation. The fibrous material represents inflammatory debris and keratin that has accumulated within the interconnected sinus tracts that form beneath the skin in hidradenitis suppurativa, as described in the context of chronic inflammatory skin disease characterized by painful, recurrent nodules and abscesses 1. Recognizing the fibroglass sign during physical examination can aid in making a clinical diagnosis of hidradenitis suppurativa without necessarily requiring a biopsy, particularly in patients with typical distribution of lesions in axillary, inguinal, perineal, or inframammary regions. Some key points to consider when evaluating the fibroglass sign include:

  • The presence of sinus tracts or lesions that can express fibrous material
  • The characteristic appearance of the fibrous material, which resembles fibreglass insulation
  • The location of the lesions, which are typically found in apocrine gland-bearing areas
  • The importance of gentle pressure in eliciting the fibroglass sign, as described in the context of evidence-based approach to the treatment of hidradenitis suppurativa/acne inversa 1. It is essential to note that while the provided evidence does not directly describe the fibroglass sign, the understanding of hidradenitis suppurativa as a chronic inflammatory skin disease supports the clinical significance of this sign in diagnosis.

From the Research

Hidradenitis Suppurativa Overview

  • Hidradenitis suppurativa is a chronic inflammatory disease characterized by painful, deep-seated nodules, abscesses, and draining tunnels in the skin of axillary, inguinal, genitoanal, or inframammary areas 2.
  • The disease typically starts in the second or third decade of life, with an average worldwide prevalence of 1% 2.
  • Hidradenitis suppurativa has a profound negative effect on patients' quality of life and is often accompanied by comorbidities such as metabolic syndrome, inflammatory arthritis, and inflammatory bowel disease 2, 3.

Clinical Presentation and Diagnosis

  • The clinical presentation of hidradenitis suppurativa ranges from rare, mild inflammatory nodules to widespread abscesses, sinus tracts, and scarring 3.
  • The disease is associated with several comorbidities, including diabetes mellitus and Crohn disease 3.
  • Quality of life is often affected, and patients should be screened for depression 3.

Treatment Options

  • Treatment includes wearing loose-fitting clothes, losing weight if overweight, and smoking cessation 3.
  • Topical clindamycin alone can be effective for patients with mild disease, while oral antibiotics such as tetracyclines may be used for moderate disease 3.
  • Adalimumab, a tumor necrosis factor alpha inhibitor, is effective for patients with moderate to severe hidradenitis suppurativa 3.
  • Surgical procedures, including local procedures and wide excision, may be necessary for definitive treatment 3, 4.

Fibroglass Sign

  • There is no specific mention of the "fibroglass sign" in the provided studies 2, 3, 4, 5, 6.
  • The studies focus on the clinical presentation, diagnosis, and treatment of hidradenitis suppurativa, but do not mention a specific "fibroglass sign" associated with the disease.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Hidradenitis suppurativa.

Lancet (London, England), 2025

Research

Hidradenitis Suppurativa: Rapid Evidence Review.

American family physician, 2019

Research

Hidradenitis suppurativa: pathogenesis and management.

British journal of plastic surgery, 2003

Research

Hidradenitis Suppurativa: Causes, Features, and Current Treatments.

The Journal of clinical and aesthetic dermatology, 2018

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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