Cystic lung disease in Birt-Hogg-Dubé syndrome. A case series

Abstract

Birt-Hogg-Dubé syndrome (BHDS) is a rare autosomal dominant inherited disease caused by mutations in the folliculin (FLCN) gene. It is characterized by lung cysts, skin fibrofolliculomas and an increased risk for the development of renal cancer, especially chromophobe. Lung cysts in the context of BHDS are typically lower lobe predominant, paramediastinal, in relation to the fissures and often elliptical shaped. Skin manifestations can easily go unnoticed. Respiratory physicians need to have a high degree of vigilance as they can be the first to suspect the disease in the setting of diffuse cystic lung disease. Meticulous skin examination and referral to a dermatologist is of utmost importance as it can establish the diagnosis in the least invasive way. Correct diagnosis is crucial as it may allow for genetic counseling to the affected family and the implementation of a monitoring strategy for early detection of renal cancer.

Fig. 1

White dome-shaped papules (A–B). Dermatoscopically the lesions show a structure-less pale white coloration, roundish contour and well-demarcated borders. Clues of chronically sun-exposed skin such as solar lentigos (brown spots) can also be detected at the peri-lesional skin (C–D). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 2

Multiple bilateral cysts are noted with normal intervening parenchyma. Some of the cysts are paramediastinal and in relation to the fissures with an elliptical shape (A–B). An elliptical bilobated cyst is noted in the right middle lobe (C). The cysts are predominantly located in the lower lobes (D).

Fig. 3

Proliferation of follicular epithelium surrounded by a perifollicular fibrous sheath.

Fig. 4

A few numbers of white, dome-shaped papules on the frontal and lateral face are noted (white arrows) (A–B). Dermatoscopic examination reveals lesions with pale white areas and a hint of circular structures correlating with follicular openings (black arrows). Dermatoscopy was very helpful both in terms of diagnosis and as a guide for the selection of the precise site of skin biopsy (C–D).

Fig. 5

Multiple bilateral cysts are noted with normal intervening parenchyma. A bilobated cyst is noted (A). A cyst in the right middle lobe is in relation to the major fissure (B).