2 Developmental and Congenital Conditions
Diffuse White Lesions
Diffuse white developmental conditions are often dyskeratotic lesions and represent oral manifestations of genodermatoses. Oral lesions seen in dyskeratosis congenita are usually oral dysplasias/leukoplakias; oral lesions of pachyonychia congenita are rarely biopsied. Oral lesions of hereditary mucoepithelial dysplasia, a condition of defective expression of cytoskeleton-junctional elements, presents as erythematous mucosa.
This is a rare, autosomal dominant conditions resulting from a mutation of the helical domain on K4 (chromosome 12q) and K13 (chromosome 17q) leading to keratin instability and abnormal tonofilament aggregation.
• Variable parakeratosis, benign epithelial hyperplasia with “spongy appearance” caused by cytoplasmic vacuolation (from glycogen) and not true spongiosis; minimal to no inflammation (Fig. 2-2, A and B)
• Perinuclear eosinophilic condensations of keratin and dyskeratotic cells sine qua non for diagnosis (see Fig. 2-2, C); rare cases with epidermolytic hyperkeratosis
FIGURE 2-2 White sponge nevus. A, Benign epithelial hyperplasia with pale “spongy” appearance. B, Intracellular vacuolation and dyskeratosis sparing basal cells; inset shows PAS-positive, diastase-labile intracytoplasmic granules typical for glycogen. C, Perinuclear condensations and cytoplasmic vacuolation (not spongiosus).
Treister N, Lehmann LE, Cherrick I, et al. Dyskeratosis congenita vs. chronic graft versus host disease: report of a case and a review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004;98:566-571.
Hereditary Benign Intraepithelial Dyskeratosis
Darier Disease (Keratosis Follicularis) and Warty Dyskeratoma
• Darier disease characterized by white, painless, keratotic papules (seen in mild disease) or plaques and cobblestoning of the mucosa (seen in more severe disease) in 10% to 50% of patients with skin disease (Fig. 2-4); onset in first and second decade; lesions on palate, gingiva or tongue; skin findings invariably present; up to one third of cases with parotid or submandibular swelling likely because of strictures and obstruction
Darier disease is an autosomal dominant disorder associated with a mutation of ATP2A2 gene (on chromosome 12q) involved in cytoplasmic calcium transport that is required for proper functioning of desmosomes and keratin formation, resulting in dyscohesion. Warty dyskeratoma is of unknown etiology but has the same histology.
• Often umbilicated/crateriform hyperkeratosis, elongated, slender rete ridges 3 to 8 cells wide, and suprabasilar acantholysis with villous-like projections of connective tissue papillae rimmed by basal cells; dyskeratotic cells with dark nuclei in the form of slender grains (needle-shaped) or corps ronds (round) may not be prominent; variable chronic inflammation (Fig. 2-5)
Nodular or Tumor-Like Lesions
FIGURE 2-8 Sebaceous hyperplasia. A, Many lobules of sebaceous glands in the lamina propria without hyperplasia of germinative layer. B, Mature sebocytes without proliferation of germinative cells, and secretions in duct.
Azevedo RS, Almeida OP, Netto JN, et al. Comparative clinicopathological study of intraoral sebaceous hyperplasia and sebaceous adenoma. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;107:100-104.
Kaminagakura E, Andrade CR, Rangel AL, et al. Sebaceous adenoma of oral cavity: report of case and comparative proliferation study with sebaceous gland hyperplasia and Fordyce’s granules. Oral Dis. 2003;9:323-327.