[Hornstein-Knickenberg and Birt-Hogg-Dube syndrome. Report of a case with spontaneous pneumothorax and aplasia of the left internal carotid artery].

A 36-year-old man presented with multiple skin-colored papules on his face, neck and back of several years duration. His father, sister and probably his grandfather suffered from similar skin lesions. The histological examination revealed fibrofolliculomas in all three cases. At the age of 33 years the patient developed a spontaneous pneumothorax, and one year later a subarachnoidal hemorrhage due to aplasia of the left carotid artery. His grandfather had died from metastatic rectal carcinoma. A diagnosis of Hornstein-Knickenberg-/Birt-Hogg-Dubé syndrome was made, which is characterized by fibrofolliculomas and colon adenomas. Our familial observation speaks in favor of autosomal dominant transmission of the Hornstein-Knickenberg-/Birt-Hogg-Dubé syndrome. Apart from the skin several other organs may be involved, including the kidneys, urogenital tract, eyes and endocrine system. By this report we wish to draw intention to the typical skin lesions which can be the marker for neoplasia and other characteristic associated findings.