Birt-Hogg-Dube syndrome

An alternative name is fibrofolliculomas with trichodiscomas and acrocordons. Alternatively, BHD syndrome is rather easier. It is named after the 3 authors of a paper in 1977.¹

It is a rare inherited genodermatosis characterized by hair follicle hamartomas, kidney tumours, and spontaneous pneumothorax.² A hamartoma is a benign tumour that contains tissue that is normally present at that site but in a disordered structure.

The mutation is at gene map locus 17p11.2.³

It is very rare in that it was first described in 1977 and further reports in the literature are of further families. There is no report of general prevalence. The original paper reported on 15 affected members of 70 studied in a family.¹

It appears to be inherited as an autosomal dominant.

• Skin lesions develop in the 20s or 30s and remain throughout life. They are small, papular skin lesions, about 2 to 4mm in diameter, that develop slowly over the scalp, face, neck, and upper trunk. They may also be seen in the mouth. They cause no symptoms and the reason for presentation is cosmetic.
• Acrochordons are small, soft, furrowed, papules, just 1 or 2mm in diameter, that may be found on the eyelids, neck, axilla, and upper half of the trunk.
• Other reported features include polyps of the oral mucosa, collagenomas, angiolipomas, and deforming lipomas.
• A fairly common finding is renal cell carcinoma that may be multiple and bilateral. This tends to present rather later than the skin lesions. The commonest histology is chromophobe renal carcinoma that is an uncommon form.⁴
• Renal oncocytoma is also reported.
• Spontaneous pneumothorax is a risk. This is appaently associated with pulmonary cysts.
• Medullary thyroid cancer was reported in 9 members of the original family described by Birt, Hogg, and Dube, but it has not been reported since.
• There have been reports of colonic polyps and carcinoma of colon⁵ but these are variable and an increased risk for colonic polyps and malignancy is debated.⁴

The diagnosis should be considered when there is familial renal carcinoma or chromophobe renal carcinoma that is a rare form. There are implications for other members of the family.

Normally, the histology of renal carcinoma is clear cell carcinoma 75%, papillary renal tumour 15%, oncocytoma 5%, and chromophobe 5%.⁶ In a study of 130 renal tumours found in 30 BHD patients, the spectrum of renal histology included 34% chromophobe, 5% oncocytoma, 50% chromophobe/oncocytic hybrid, 9% clear cell, 2% papillary.⁷

• Skin biopsy is necessary to confirm the nature of the lesions.
• Chest x-ray may show cysts.
• Renal ultrasound is necessary in case of renal carcinoma or oncocytoma. The latter is benign.

There must be long term follow up for malignant change, especially renal carcinoma.

There is no specific therapy. Skin lesions may be treated by surgical removal. Dermabrasion and electrodessication have been used but the lesions may recur. Laser treatment seems promising.

Genetic counselling should be offered.

The tendency for internal malignancy seems variable and may vary between families. The risk of renal or other malignancies is significantly higher than for the general population and risk seems to vary between families studied but most individuals with BHD will not suffer such a malignancy. It is not an invariable part of the disease.

The skin lesions are not harmful. Prognosis is dependent upon the possibility of internal, especially renal malignancy.

The prognosis is insufficiently poor to merit prenatal screening.