Fibrofolliculomas In Birt-Hogg-Dube Syndrome Guide

Fibrofolliculomasare small dome-shaped, whitish-yellow papulescommonly seen on the face, neck, and upper trunk in adults with BirtHoggDub syndrome(BHD).

What is Birt-Hogg-Dub syndrome?

Birt-Hogg-Dub (BHD) syndrome is a rare autosomal dominant genodermatosis characterized by cutaneous fibrofolliculomas, pulmonary cysts predisposing to spontaneous pneumothorax, and an increased risk of renal neoplasms. First described in 1977 by Canadian physicians Arthur R. Birt, Georgina R. Hogg, and William J. Dub, the syndrome arises from germline mutations in the FLCN gene on chromosome 17p11.2, which encodes folliculin, a tumor suppressor protein involved in regulating cell growth and metabolism.

The skin manifestations, particularly fibrofolliculomas, are the most frequent clinical feature, occurring in approximately 85% of affected individuals, typically appearing after age 20 and increasing in number with age. While benign, these lesions serve as critical diagnostic markers prompting evaluation for potentially life-threatening pulmonary and renal complications.

Clinical features

Fibrofolliculomas present as multiple, asymptomatic, 2
34 mm smooth, dome-shaped, flesh-colored to whitish papules predominantly on the face (cheeks, nose, forehead), neck, ears, and upper trunk. They may also involve the scalp and oral mucosa. Lesion density varies widely, from a few to hundreds, and they are often mistaken for acne, trichoepitheliomas, or basal cell carcinomas.

Associated skin lesions include:

• Trichodiscomas: Similar pale papules distinguished histologically by a fibrous stroma with thin epithelial strands; many experts consider them synonymous with fibrofolliculomas.
• Acrochordons (skin tags): Soft, pedunculated growths, though nonspecific.
• Rare findings: Perifollicular fibromas, collagenomas, angiolipomas, oral mucosal polyps.

BHD also features bilateral basilar lung cysts (70
380% of cases), with 25% risk of recurrent pneumothorax, often presenting before skin lesions. Renal tumors occur in 15
30% of patients, typically multifocal and bilateral, including hybrid oncocytic/chromophobe tumors (most common), oncocytomas, and chromophobe renal cell carcinomas; onset averages age 50.

Images

The following high-resolution clinical images illustrate characteristic fibrofolliculomas in Birt-Hogg-Dub syndrome:

• Image 1: Multiple whitish dome-shaped papules symmetrically distributed on the cheeks and nasal bridge of a 45-year-old male patient, highlighting the classic facial involvement.
• Image 2: Close-up of neck lesions showing 2
  33 mm smooth, asymptomatic papules coalescing into plaques, with subtle telangiectasia.
• Image 3: Upper chest presentation with scattered flesh-colored papules amid normal skin, demonstrating progression in older lesions.
• Image 4: Ear lobe involvement with clustered small papules, an underrecognized site.
• Image 5: Comparative view pre- and post-laser treatment, showing effective cosmetic reduction without scarring.

These images underscore the lesions’ uniformity and predilection for adnexal-rich areas, aiding clinical recognition.

Histopathology

Skin biopsy is diagnostic, revealing characteristic features of fibrofolliculoma:

• Central dilated hair follicle with thin epithelial strands radiating into loose fibrous stroma.
• Sebaceous glands and clefts between stroma and epithelium.
• Trichodiscomas show a discoid fibrous plaque with delicate epithelial cords.

Immunohistochemistry may demonstrate loss of folliculin expression. Lung cysts are thin-walled and basilar; renal tumors exhibit oncocytic morphology with eosinophilic cytoplasm and perinuclear halos.

Diagnosis

Diagnosis combines clinical criteria, family history, and genetic testing:

Presence of 1 major or 2 minor criteria confirms diagnosis. Genetic testing detects FLCN mutations in >90% of cases.

Management

Skin lesions: Primarily cosmetic; options include:

• Laser therapy (CO2, Nd:YAG, erbium:YAG) for ablation.
• Electrodesiccation, curettage, or excision for isolated lesions.
• Topical retinoids or podophyllin may reduce lesion burden.

Pulmonary surveillance: Baseline HRCT; annual monitoring if cysts present. Pneumothorax management per standard protocols; pleurodesis for recurrences.

Renal surveillance: Multiphasic MRI or CT every 1 13 years from age 20, lifelong. Partial nephrectomy preferred for tumors. Colonoscopy if family history of polyps.

Genetic counseling is essential given 50% inheritance risk.

Differential diagnosis

• Multiple trichoepitheliomas: Firmer, more indurated; Brooke-Spiegler syndrome.
• Rombo syndrome: Atrophoderma vermiculatum, milia, hypotrichosis.
• Cowden syndrome: PTEN hamartomas, thyroid/breast cancer risk.
• Tuberous sclerosis: Angiofibromas, shagreen patches.
• Follicular infundibulum tumor: Solitary, non-hereditary.

Frequently asked questions

What causes fibrofolliculomas in BHD?

Germline FLCN mutations disrupt folliculin, leading to dysregulated folliculosebaceous proliferation.

Are fibrofolliculomas cancerous?

No, they are benign, but signal need for renal/pulmonary screening.

When should screening begin?

Renal imaging at age 20; pulmonary evaluation upon skin diagnosis.

Can BHD be cured?

No, but surveillance enables early intervention, improving outcomes.

Is genetic testing recommended for family members?

Yes, cascade testing for first-degree relatives.

Related topics

• Birt-Hogg-Dub syndrome
• Fibrofolliculoma
• Trichodiscoma
• Pneumothorax
• Renal cell carcinoma

Medha Deb

Health Writer