Entry from Leiber, Bernfried Die klinischen Syndrome: Syndrome, Sequenzen und Symptomenkomplexe [The Clinical Syndromes: Syndromes, Sequences, and Symptom Complexes] 7 th edition, completely reworked Volume 1: Clinical pictures Pachyonychia congenita Syn: Jadassohn-Lewandowsky Syndrome Def.: Autosomal dominant hereditary keratinization disorder with characteristic nail thickening. A 1 .: First description 1906 by the German dermatologists Josef Jadassohn, 1863-1936, and Felix Lewandowsky, 1879-1921. Diagnostic criteria: (1) Massive nail thickening of all fingers and toes, sometimes already present at birth, gradually increasing. Thickening increases toward the distal end; concurrent transversal curvature. – (2) Dirty yellow-brown discoloration of the nail. – (3) Circumscribed symmetrical hyperkeratoses on the palms and soles. – (4) Blistering in warm conditions (palmo-) plantar. – (5) Hyperhidrosis palmoplantaris. – (6) Follicular keratoses predominantly on the elbows and knees with overall dry skin, occasionally signs of ichthyotic skin. – (7) Leukoplakias of the oral mucosa. – (8) Natal teeth. – (9) Steatocystoma multiplex. – (10) In adults, corneal dystrophy possible, cataract, reticular pigmentation. Hearing impairment, hypotrichosis, hoarseness. Etiology. Autosomal dominant hereditary keratinization disorder with variable expression and incomplete penetration of the gene. Pathog.: Unknown. Remarks: Type 1 (Jadassohn-Lewandowsky): with leukoplakias and plantar bullae. Type II: without leukoplakias, minor keratoses. Type III: premature dentition with natal teeth and minor keratoses. In 3 cases, autosomal recessive transmission was claimed; however, the clinical picture was not typical. Type IV: with spotty pigmentation on the throat, axillae, trunk, thighs, and the backs of the knees, which, like the nail changes, recede in adulthood. Histological: Pigmentation incontinence and subepidermal amyloid deposits. Lit.: Jadassohn J. Lewandowsky F (1906): Pachyonychia congenita. Keratosis disseminata circumscripta, tylomata, leucokeratosis linguae. Iconographia Dermatologica. Tab 6, Vienna, Berlin. – Reich H (1980) Jadassohn-Lewandowsky Syndrom: Haut-Auge-Mund und Zahn- Kehlkopf-Nervensystem. [Jadassohn-Lewandowsky Syndrom: Skin-Eye-Mouth and Tooth- Larynx-Nervous System]. Therapiewoche 30: 6247. 1 Translator's note: Key not available. First description?