CLASSIC AND OCCULT SUBMUCOUS CLEFT PALATES - A HISTOPATHOLOGIC ANALYSIS

Objective: Although classic and occult submucous clefts have been well described with respect to clinical features and endoscopic findings, there is a paucity of information regarding the histologic characteris tics of the midline palatal area and its role in the clefting process. This preliminary study describes the histopathologic features of clas sic and occult submucosal clefts. Design: Twenty-eight patients with c lassic submucous cleft (12 patients) and occult submucous cleft (16 pa tients) were available for study, Histopathologic evaluation of two bi opsies from each patient (muscular uvulae biopsy; levator muscle bundl e biopsy) was performed. Results: Submucosal fibrosis with relatively dense collagen deposition was noted in both the musculus uvulae and le vator muscle bundle biopsy sites. Individual myocytes and myocyte fasc icles were entrapped and encased by fibrotic tissue, resulting in disr uption of the fascicular organization. Most fascicles were disrupted b y intervening dense collagen bands within and interposed between the f ascicles, The myocytes had an atrophic or hypoplastic appearance with cross-sectional diameters ranging from 42% to 61% (mean reduction, 53% ) less than those expected for myocytes from normal palates, There was fascicular disorganization with intermixing of longitudinally and cro ss-sectionally oriented myocyte groups, Minor salivary glands were aff ected as well with increased collagen deposition between and within lo bules of salivary gland tissue. Conclusions: This histopathologic stud y indicates that significant fibrosis is present within submucosal cle ft regions and is associated with myocyte atrophy or hypoplasia, The r elatively dense fibrosis appears to be a well-organized, chronic proce ss and is present in the absence of significant chronic inflammation. In addition, there is myocyte fascicular disorganization with a haphaz ard arrangement, This disorderly arrangement may imply that there is a failure of resorption of the epithelial/mesenchymal tissue during pal atine shelf closure with retention of mesenchymal tissue that contains the insertion of the velopharyngeal musculature apparatus.