In 1985, Starink et al. described patients with hereditary multiple trichodiscomas, a skin condition which was proposed to be distinct from Birt-Hogg-Dubé syndrome. However, trichodiscomas are firm, skin-coloured flat or dome-shaped papules, and their similarity to fibrofolliculomas has meant that this condition has not been widely recognised as a separate entity from BHD. Consequently, a more recent study has sought to re-evaluate these hereditary multiple trichodiscomas and suggests that they are indeed different, and has renamed this condition familial multiple discoid fibromas (FMDF) to emphasise this distinction (Starink et al., 2011).
In this study, clinical and genetic analysis was undertaken in 9 families which displayed an autosomal dominant pattern of trichodiscomas. It could be seen that the skin lesions had an early onset, usually in childhood or early adolescence, and that they were often found on the ears. In contrast, the skin lesions in BHD syndrome have a later onset in life, and occur mainly on the face and upper torso, rather than on the ears. Histologically, the lesions also showed the characteristic features of discoid fibromas, with many showing a hair follicle at their periphery. This last finding is of particular interest as the fibrofolliculomas observed in BHD often have a distorted hair follicle in the centre of the lesion, and this is notably absent in all of the samples biopsied by Starink et al. (2011). Additionally, there appeared to be no pathogenic FLCN mutations detected, as well as no cases of renal cell carcinoma and recurrent pneumothorax in the family members studied.
This work highlights the importance of clinical symptoms, family and medical history and genetic analysis in disease diagnosis, as well as emphasising the need for better histological classification of the skin lesions involved in both FMDF and BHD. Nevertheless, further research is necessary to see if there are any other associated symptoms with FMDF and to assess its prevalence. Additionally, the identification of an associated gene-defect would also aid the diagnosis and management of this condition, and may shed some light on the skin phenotype observed in BHD syndrome.
- Starink TM, Houweling AC, van Doorn MB, Leter EM, Jaspars EH, van Moorselaar RJ, Postmus PE, Johannesma PC, van Waesberghe JH, Ploeger MH, Kramer MT, Gille JJ, Waisfisz Q, & Menko FH (2011). Familial multiple discoid fibromas: A look-alike of Birt-Hogg-Dubé syndrome not linked to the FLCN locus. Journal of the American Academy of Dermatology PMID: 21794948
- Starink TM, Kisch LS, & Meijer CJ (1985). Familial multiple trichodiscomas. A clinicopathologic study. Archives of dermatology, 121 (7), 888-91 PMID: 4015134