1.17 Dyskeratosis Congenita
Definition: Dyskeratosis congenita, or Zinsser–Engman–Cole, syndrome is an uncommon disorder with great genetic heterogeneity.
Etiology: Genetic. It is usually transmitted via an X-linked trait and rarely via an autosomal dominant and autosomal recessive trait.
Clinical features: Clinically, dyskeratosis congenita is characterized by hyperpigmentation, telangiectasias, and atrophic skin areas, primarily on the neck, chest, and upper arms (▶ Fig. 1.37). Dystrophic nails, hyperhidrosis of palms and soles, skin and mucosal bullae, chronic blepharitis, continuous lacrimation, anemia, leukopenia, thrombopenia, pulmonary and gastrointestinal disorders, mental retardation, and oral lesions may occur. The oral lesions consist of recurrent blisters, epithelial atrophy, and leukoplakia (▶ Fig. 1.38). Malignant transformation of leukoplakia may occur. Dental anomalies may be observed. Increased risk for malignancies is possible. The diagnosis is based on the history and clinical features.
Laboratory tests: Histopathologic examination if complications are suspected.
Differential diagnosis: White sponge nevus, pachyonychia congenita, epidermolysis bullosa, graft versus host disease, leukoplakia, and lichen planus.
Treatment: Supportive. The management of the disease requires multidisciplinary care.
Fig. 1.37 Dyskeratosis congenita, pigmentation, and atrophy of the skin.
Fig. 1.38 Dyskeratosis congenita, leukoplakia on the dorsum of the tongue.
1.18 Pachyonychia Congenita
Definition: Pachyonychia congenita is an uncommon genodermatosis.
Etiology: Genetic. The disorder is inherited in an autosomal dominant pattern. It is classified into two major types: type I (Jadassohn–Lewandowsky) and type II (Jackson–Lawler), depending on the affected gene.
Clinical features: Clinically, the disorder is characterized by symmetrical nail thickening (▶ Fig. 1.39), palmoplantar hyperkeratosis, hyperhidrosis, blister formation on the soles, follicular keratosis, hoarseness, dyspnea, and oral lesions. The oral lesions appear at birth or shortly thereafter and only in type I of the disorder. The oral mucosa appears as thick, white or grayish-white asymptomatic plaques, usually on the buccal mucosa, tongue, palate, and gingiva (▶ Fig. 1.40). The diagnosis is based on the history and clinical features.
Differential diagnosis: Dyskeratosis congenita, focal palmoplantar and oral mucosa hyperkeratosis syndrome, white sponge nevus, hereditary benign intraepithelial dyskeratosis, and leukoplakia.
Treatment: The treatment is symptomatic.
Fig. 1.39 Pachyonychia congenita, thickening of the toe nails.
Fig. 1.40 Pachyonychia congenita, hyperkeratosis of the buccal mucosa.
1.19 Focal Palmoplantar and Oral Mucosa Hyperkeratosis Syndrome
Definition: It is a rare mucocutaneous disorder.
Etiology: Genetic. It is inherited in an autosomal dominant trait.
Clinical features: Clinically, the disorder is characterized by focal hyperkeratosis at the weight-bearing and pressure-related areas of the palms and soles (▶ Fig. 1.41) and the oral mucosa, mainly the attached gingiva (▶ Fig. 1.42), and less frequently at other oral regions (e.g., palate, lateral border of the tongue, and retromolar area). The oral manifestations present as white hyperkeratotic plaques (leukoplakia). Nail thickening and hyperhidrosis may occur. The lesions usually develop in early childhood and the diagnosis is based on the history and clinical features.
Differential diagnosis: Pachyonychia congenita, dyskeratosis congenita, white sponge nevus, focal palmoplantar hyperkeratosis, and leukoplakia.
Treatment: The treatment is symptomatic. Systemic retinoids may be helpful for skin lesions.
Fig. 1.41 Focal palmoplantar and oral mucosa hyperkeratosis syndrome, hyperkeratosis of the fingers, and thickening of the nails.
Fig. 1.42 Focal palmoplantar and oral mucosa hyperkeratosis syndrome, leukoplakia of the maxillary attached gingiva.
1.20 Mucosal Horn
Definition: Mucosal horn is a rare benign lesion of the oral mucosa analogous to cutaneous horn.
Etiology: The cause is keratin accumulation.
Clinical features: Clinically, mucosal horn appears as straight or slightly convex keratin projection of few millimeters to 1 cm or more in length with characteristic white color (▶ Fig. 1.43). Similar lesions can be observed on the glans penis and the skin. The cutaneous horn usually occurs on the face (▶ Fig. 1.44). The diagnosis is based on the clinical features and should rarely be confirmed histologically.
Laboratory tests: Histopathologic examination.
Differential diagnosis: Papilloma, verruca vulgaris, condyloma accuminatum, leukoplakia, and squamous cell carcinoma.
Treatment: The treatment of choice is conservative surgical excision.
Fig. 1.43 Mucosal horn on the lingual mucosa.
Fig. 1.44 Cutaneous horn on the skin of the cheek.
1.21 Papilloma
See also sections 6.1, and 8.1.1.
Definition: It is a benign tumor of the oral mucosa.
Etiology: The exact etiology is unknown. In 50 to 60% of papillomas, HPV types 6 and 11 are detected within the lesion.
Clinical features: Clinically, papilloma presents as an asymptomatic exophytic, well-circumscribed, pedunculated or sessile tumor with multiple, small finger-like projections that give it a cauliflower-like