Congenital Hemifacial Hyperplasia: An Embryologic Hypothesis and Case Report RicHaArDp A. M.D. M. HaskeLt Newman, M.D. R. Buroi, PH.D. DonaLp P. Conpit, M.D. Congenital hyperplasia is a developmental disorder characterized by marked unilateral asymmetry. The structural disproportions from one side to the other far exceed variations commonly seen in the normal population. Classically, as first described in 1836, the over- growth of tissue is restricted to one-half of the body, including the extremities. In other cases the hyperplastic enlargement involves segmental areas of the body, such as the hemifacial skeleton and an extremity. A case report is presented, and the clinical characteristics of 192 cases of congenital hyperplasia in the literature are briefly re- viewed. Use of the word hyperplasia to describe the condition (rather than hypertrophy) is encouraged. The authors propose a new em- bryologic hypothesis: asymmetrical development of the neural fold and hyperplasia of the neural crest cells are said to form the basis for the disorder. The rewards, risks, and limitations of reconstructive surgery over a 10-year period are discussed. "If it is in her moments of abnormality that covering the facial skeleton are larger on Nature reveals her secrets, as Goethe once re- the left side than on the right. The ribs of marked, then the condition of hemihypertro- the thorax and the halves of the vertebral phy assumes an added piquancy of interest." bodies are larger on the right side than on A. Gesell (1927) the left. The bones of the right upper ex- tremity are longer and have greater di- Asymmetry is common and one of the ameter than those on the contralateral side more unusual and interesting errors of (Meckel, 1822; Updegraff, 1930; Haring, human reproduction. Consider the subtle 1961). Such imperfections of human anat- imperfections of human form that are omy are of little daily concern. They, in present in the average patient. The breasts, fact, often provide character and enhance pelvis, and genitalia are rarely symmetri- natural beauty (Caltagirone and Kostek1, cal. The skull and bone of the face, the 1955). _ cerebral hemispheres, and the soft tissues In patients affected by congenital hy- perplasia, asymmetry is more marked than The authors are affiliated with the University of in the normal population. The altered Michigan Medical Center. Drs. Pollock, Newman, and structural form caused by this condition is Condit are with the Section of Plastic Surgery, De- usually subtle at birth. With rapid growth, partment of Surgery. Dr. Burdi is with The Center for Human Growth and Development, Department the involved areas of the body may take of Anatomy & Cell Biology. on grotesque dimensions, leading to al- Address reprint requests to: M. H. Newman, M.D., tered form and function. The disorder may Section of Plastic Surgery, Box 22, C7028 Outpatient involve one-half of the body structure Building, University of Michigan, 1405 East Ann (Beck, 1836) or be limited to the hemlface Street, Ann Arbor, Michigan, 48109. This study was supported in part by National In- (Friedrich, 1863). stitutes of Health Research Grant DE 03610-17. This report has four objectives: (1) Re- 173 174 Cleft Palate Journal, July 1985, Vol. 22 No. 3 FIGURE 1. Hyperplasia of the tongue terminates at the midline and usually involves the anterior two-thirds of the tongue. constructive surgery in patients with con- The ipsilateral maxillary alveolar ridge was en- genital hyperplasia has seldom been re- larged. Excisional biopsy of the mass of the right corded. We present our surgical experience cheek confirmed the presence of fatty tissue over the past 10 years with one patient and without evidence of lymphangioma or vascular malformation. The limbs appeared symmetri- discuss the three basic problems facing the cal, and there was no evidence of abdominal reconstructive surgeon wishing to under- organomegaly. Congenital hemifacial hyper- take surgery in patients with congenital plasia was suspected. hemifacial hyperplasia. (2) Congenital At 8 years of age, the patient complained of asymmetry has frequently been described progressive diplopia that was enhanced when as congenital Aypertrophy. The authors em- gazing to the right. Orbital dystopia with hy- phasize the importance (based on histo- pertrophy of the bony orbit, elevation of the pathology) of using the term congenital right globe, and ectropion of the right lower hyperplasia. (3) Prior to this report, the eyelid associated with mild gaze strabismus were clinical characteristics of congenital hyper- noted. Clinical studies also revealed an over- growth of membranous bone and soft tissue of plasia have not been well tabulated. Infor- the right face and a downward slope of the oc- mation available from 192 cases in the lit- clusal plane to the right (Fig. 2). Enlargement erature are therefore briefly reviewed. (4) of the first rib was noted on chest radiographs Early theories regarding the embryology (Fig. 3). of congenital hyperplasia failed to ac- By late adolescence the patient complained of knowledge the role of the neural tube as severe malocclusion, and partial correction of the developmental template for body size the osseus contour defect and operative cor- and symmetry. The authors offer a new rection of the malocclusion (Figs. 4 and 5) were embryologic hypothesis to explain the accomplished by wedge Le Forte I maxillary clinical characteristics seen in this and other ostectomy, simultaneous bilateral vertical ra- case reports. mus osteotomy of the mandible, and osseus contouring of the zygoma, bony orbit, and right Case Report mandibular body (Figs. 6, 7, and 8). A white female was delivered vaginally without Despite significant improvement in the con- forceps at term weighing 9 lbs following an tour of the facial bone and establishment of a uneventful pregnancy. Physical examination was functional horizontal occlusal relationship, the unremarkable except for the presence of a right persistant soft tissue enlargement and facial cheek mass which clinically suggested a lym- sagging limited the desired cosmetic improve- phangioma. An incisional biopsy of the mass in ment. At age 13, a lower lip cheiloplasty, par- the neonatal period revealed adipose tissue. tial glossectomy, and rhytidectomy were per- When the patient was 5 years of age, enlarge- formed and resulted in a slight improvement. ment of the right tongue to the midline was A suspected right facial paralysis was not con- noted (Fig. 1). The tongue deviated to the left. firmed electromyographically, and the distor- Pollock, Newman, Burdi, and Condit, CONGENITAL HEMIFACIAL HYPERPLASIA 175 tion of facial sagging was presumed to reflect tissue mass. A temporalis fascial sling suspen- sion partially corrected the problem (Fig. 9). Since age 16, the patient has shown minimal progression of the hyperplastic process (Fig. 10). Her occlusion has remained stable (Fig. 11). NOMENCLATURE Until 1947 the histology of congenital hyperplasia was presumed to be an en- largement of individual cells. Sutton biop- sied the facial musculature of a 6-month- old child with congenital hemifacial hy- perplasia. The individual muscle fibers were not enlarged when inspected under light microscopy. A more sophisticated histologic survey of the organs of a 13-year- old male with generalized involvement failed to reveal cellular enlargement in any of the organs examined. Facial skin, fat, blood vessels, muscle, nerve, and bone from the patient in this report were also studied by light micros- copy. The cells were normal in size, shape, and distribution. The histopathology is an increase in the number of cells (hyperpla- sia) rather than an increase in cell size (hy- FIGURE 2. The patient is pictured in mid-ado- pertrophy). lescence with marked facial asymmetry caused by an Like Geiser et al (1970), the authors overgrowth of the mandible, maxilla, and zygoma, as conclude that use of the term congenital well as hyperplasia of the parotid gland and masseter muscle. Note the enlargement of the right upper lip hemifacial hyperplasia is more histologi- and aberrent occlusal plane. cally precise and clinically appropriate FIGURE 3. A chest ra- diograph revealed a hyper- plastic right rib without other abnormality. 176 Cleft Palate Journal, July 1985, Vol. 22 No. 3 FIGURE 4. This view demonstrates the downward slope of the occlusal plane. Note the diastemata of the maxillary and mandibular teeth. FIGURE 5. Panoramic radiographs document ab- normalities of the occlusal plane, enlargement of the right mandible and maxilla, and the presence of macro- dontia. FIGURE 6. This illustration summarizes the sur- - gical procedures the patient underwent at age 11. Orthodontic procedures are not depicted. A, a pre- operative view is shown. B and C depict the osteo- tomies and bone excision accomplished using power driven burrs. D demonstrates preservation of the in- ferior alveolar nerve during osteotomy and contour- ing of the right mandible. Pollock, Newman, Burdi, and Condit, CONGENITAL HEMIFACIAL HYPERPLASIA 177 cross-sectional enlargement of the extrem- ities (Peabody, 1936; Bryan et al, 1958; Macewen, 1967). Anomalies of the rib cage, vertebrae, and pelvis are common. Multi- ple anomalies are found in scattered case descriptions (Table 2). Patients exhibit clinically or at autopsy: enlargement of the spleen, liver, kidney, or adrenal glands (Ringrose, 1965; Gorlin, 1962; Geormaneanu et al, 1983). The fre- quency of benign and malignant tumors of the viscera is increased particularly in those organs commonly affected by hy- perplasia (Geormaneanu et al, 1983; Geiser et al, 1970; Schwartzman et al, 1942; Hutchinson, 1915; Harwood and O'Flynne, 1935; Roth, 1938; MacNab, 1952; Riedel, 1952; Benson et al, 1963; Fraumeni and Miller, 1967). In two studies the brain was enlarged on the side of the skeletal in- volvement (Ward and Lerner, 1947; Geiser et al, 1970). Microscopic study of central nervous system tissue has not otherwise been described. FIGURE 7. This radiograph (frontal view) was taken following osteotomies of the maxilla, mandible, and zygoma depicted in Figure 5.