Laryngeal features in Lipoid proteinosis: a systematic review and meta‑analysis of individual participant data

Purpose Lipoid proteinosis (LP) or Urbach-Wiethe disease (OMIM 247100) is a rare syndrome characterised by early vocal folds infiltration and subsequent multi-organ involvement. LP is often unrecognised and its associated hoarseness is overlooked. The main objective of the study was to investigate hoarseness in LP and implement a diagnosis among otolaryngologists. Methods PubMed/MEDLINE and OMIM databases were systematically searched. Authors concentrated the search on published articles starting from the discovery of the pathogenesis of LP by Hamada et al. in 2002. Only cases in which a diagnosis was reported both clinically and through biopsy and/or genetic molecular testing were included. Characteristics of the LP cases were extracted from each included study. Results were obtained through Generalized Estimating Equations. Results The search strategy yielded 217 articles, of which 74 (34.1%) met the selection criteria. A total of 154 cases were included. Hoarseness was described in all LP cases and clearly stated as the onset symptom in 68.8%. The onset was on average at 19 months of age (CI: 3.00–20.00), while the mean age at diagnosis was 15 years (CI: 10.00–30.00). Therefore, the diagnostic delay amounted to 13.42 years (CI: 8.00–23.83). Hoarseness alone was responsible for an LP diagnosis in only 14.3% of cases. In 43.5% of cases, genetic analysis of the ECM1 gene was performed and exon 6 was the most frequently altered portion. Conclusion Analysing the largest number of published cases, the study underlined that hoarseness is the key symptom for diagnosing LP since early childhood, though frequently overlooked.