Fact-sheet: Birt–Hogg–Dubé syndrome
  • Hornstein-Knickenberg syndrome
  • Fibrofolliculomas with trichodiscomas and acrochordons


Updated on 12/08/2025 at 1:56 PM

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Definition

Birt–Hogg–Dubé syndrome is a rare autosomal dominant genetic disease affecting the FLCN gene on chromosome 17p11.2, which encodes folliculin, a protein involved in cell regulation functions (tumor suppressor).

Clinical features

Young patient, 30 to 40 years old

  • Typical dermatologic involvement: fibrofolliculomas of the face and trunk
  • trichodiscomas
  • acrochordons
  • Pulmonary involvement: cysts with polyhedral contours complicated by recurrent pneumothorax
  • Renal lesions: benign oncocytomas, malignant chromophobe cell carcinomas, clear cell carcinomas or the papillary subtype
  • Possible associations with other tumor types: colon, thyroid, parotid glands, malignant melanoma

CT

Pulmonary involvement:

  • elementary lesion: cysts = air-density spaces circumscribed by a thin wall < 4mm, with irregular contours
    ≠ cavity: air-density space of variable thickness within a consolidation, mass or nodule
    ≠ emphysema: no wall, centrilobular artery
  • distribution: subpleural predominance, lower and middle fields
  • Perivascular distribution
  • complication: pneumothorax

Renal involvement:

  • oncocytoma: iso/hypodense, early homogeneous enhancement,
    absence of calcification, hemorrhage or signs of extension
  • multiple chromophobe carcinoma: well-circumscribed mass, isodense and homogeneous, ± punctate calcifications, moderate and homogeneous enhancement,
    classically no hemorrhage, necrosis or renal vein invasion

MRI

Oncocytoma:

  • slight T1 hyposignal, T2 hypersignal (tumor stroma), homogeneous enhancement
  • if ≥ 3cm: eccentric or central scar, stellate or polygonal in shape
    (fibrous scar) with T1 hyposignal and T2 hypersignal (myxoid component)

Chromophobe carcinoma:

  • T1 isosignal, T2 hyposignal, moderate homogeneous enhancement

Management

Diagnosis clinically suspected, confirmed by genetic analysis

Differential diagnosis

Differential diagnoses of pulmonary cystic disease:

  • Langerhans cell histiocytosis: young smoking male, irregular lace-like forms, upper and middle lobe predilection, presence of nodules
  • Lymphangioleiomyomatosis: woman of childbearing age, diffuse homogeneous distribution
  • Lymphocytic interstitial pneumonia (LIP): ground-glass opacities surrounding the cysts, distribution along bronchovascular bundles