Oral White Sponge Nevus in a Four-Generation Family: Case Report

Pornpan Youngnak-Piboonratanakit (1), Kittipong Dhanuthai (2)

Affiliation:

1 - Department of Oral Medicine, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330, Thailand
2 - Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok 10330, Thailand

Address for correspondence:

Pornpan Youngnak-Piboonratanakit  DDS, MS, Ph.D
Chulalongkorn University
Faculty of Dentistry
Department of Oral Medicine
Bangkok 10330, Thailand
Tel : +6622188942     
Fax : +6622188941
pornpan.p@chula.ac.th

Received: September 7, 2012

Accepted: November 25, 2012

Available online: December 15, 2012

Acta Stomatol Croat. 2012;46(4):312-316.

Case report

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Abstract

White sponge nevus (WSN) is a rare benign autosomal dominant disorder which is usually manifested as soft, white, and spongy plaque involving the mucous membrane, predominantly the oral mucosa. Onset is at birth or during childhood with no gender predilection. We present a 4-year-old boy and the 42-year-old father, complaining of painless white lesions in the oral cavity. The family history revealed that of the 18 descendants, 11 (61.11%) had WSN. Clinical examination revealed diffuse, folded, spongy, white plaque involving the buccal mucosa bilaterally and other oral mucosal areas. Histological examination showed acanthosis, hyperparakeratosis, spongiosis and the presence of an eosinophilic condensation in the perinuclear region from the spinous layer. The diagnosis was established as WSN based on the positive four-generation family history, clinical and histological features. There is no specific treatment for WSN. Despite the rarity of WSN, this lesion should be included in the differential diagnosis of white lesions in childhood, especially with a positive family history.

Key Words:

Leukokeratosis, Hereditary Mucosal; Mouth Mucosa

 

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Introduction

White sponge nevus (WSN; OMIM number 193900) is a rare benign autosomal dominant disorder which affects non-keratinized stratified squamous epithelia, primarily oral mucosa (1). Extraoral sites including nasal, esophageal, laryngeal, vaginal and anal mucosa are less frequently affected (1-3). Both genders are affected equally since its trait has irregular penetration and familial cases are uncommon (4, 5). The onset of WSN usually occurs at birth or during early childhood; however, it may be detected or become more intense in puberty (1, 2, 5).
Clinically, WSN is characterized by the presence of asymptomatic, bilateral, soft, gray-white and spongy plaque. The plaque surface is thick, folded and may peel away from the underlying tissue (1, 5, 6). The buccal mucosa is the most common site, followed by the tongue, labial mucosa, lips, alveolar ridges and floor of the mouth (5). The histological features of WSN are hyperparakeratosis, acanthosis, vacuolization of the suprabasal layer of the epithelium and the characteristic perinuclear eosinophilic condensation in the upper spinous layer resulting from the abnormal aggregation of keratin intermediate filaments. The basement membrane is intact and the connective tissue usually shows no or slight inflammation (2, 3, 6, 7). There is no malignant transformation and no need for treatment (6, 8). However, some benefits have been reported with using systemic antibiotics including tetracycline and penicillin (9-11). Recent studies have reported that the mutations of the mucosal specific keratins, K4 or K13, are responsible for the development of WSN (4, 12-14).   
The aim of this paper was to describe an interesting case of WSN in a four-generation Thai family.

 

 

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Case report

A 4-year-old boy was referred to the Oral Medicine Clinic, Faculty of Dentistry, Chulalongkorn University because of the presence of asymptomatic white lesions at both sides of buccal mucosa since his birth. Oral examination revealed diffuse, non-removable, slightly raised, light spongy, white plaque involving the buccal mucosa and retromolar mucosa bilaterally (Figure 1a). The 42-year-old father reported that he also had asymptomatic extensive white plaque in his mouth since his early childhood. There were no associated extraoral lesions of their eyes, skin and other mucosal surfaces. Clinical examination revealed asymptomatic, diffuse, non-removable, thick, corrugated white plaque of the buccal mucosa, the retromolar areas, the mucobuccal folds of posterior teeth, the ventral aspects of the tongue and lower lip bilaterally (Figure 1b). The father reported that in the 4 most recent generations, 11 out of 18 descendants (61.11%) were similarly affected (Figure 2).  
The incisional biopsy of the buccal mucosa of the father was carried out due to the positive family history on the paternal side of the child, the similar clinical appearances between the lesions of the father and the child and the fatherís refusal to perform the biopsy on the child.  Biopsy report revealed that the epithelium was thickened and exhibited hyperparakeratosis, slight acanthosis and vacuolation of the cytoplasm of the cells of the spinous layer. Some cells of the spinous layer showed eosinophilic perinuclear condensation of the keratin tonofilaments. The subjacent fibrous connective tissue was normal with no signs of inflammation (Figure 3). In addition, 10% KOH smear was negative for fungal infection. Following the diagnosis of WSN, our patients received no treatment but underwent the periodic follow-up evaluations.                             

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Figure 1 Clinical features of WSN; A 4-year-old boy (a) and his 42-year-old father (b). Buccal mucosa exhibiting thickened corrugated white plaque, extending to the retromolar area

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Figure 2 Pedigree of a family affected by WSN. Affected individuals are indicated by black symbols; circles indicate females and squares indicate males; and arrow indicates the proband. Pedigree numbering system is based on the generation indicated by Roman numerals from top to bottom and numbers of the same generation were assigned Arabic numerals from left to right. For example, the proband is identified as the pedigree number IV-2

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Figure 3 Histological section of WSN exhibits hyperparakeratosis, acanthosis, and spongiosis in stratified squamous epithelium (hematoxylin and eosin stain, original magnification ī100). The inset exhibits eosinophilic perinuclear condensation of cells, from the spinous cell layer (hematoxylin and eosin stain, original magnification ī400).

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Discussion

WSN is a genetic disorder caused by mutations in the genes encoding for mucosal-specific keratins K4 and K13, which were expressed specifically in suprabasal keratinocytes of the buccal, nasal, esophageal mucosa, and anogenital epithelia and led to the characteristic mucosal white plaque (3, 4, 12). In the present paper, it was revealed that 11 out of 18 descendants (61.11%) had WSN. The affected descendents regardless of gender were the offspring of at least one affected parent reaffirming the autosomal dominant pattern of transmission. Nevertheless, the presence of WSN lesions in other five descendants was based on the fatherís account; therefore, we cannot neglect a possibility of the risk of the recall bias. The presence of oral WSN in the same family members has been reported in the previous studies (1-6, 8, 12-15). The study of WSN in a three-generation family in Brazil showed that 8 out of 23 descendants (34.78%) were affected (5) and 18 out of 43 descendants (41.86%) were noted for a four-generation Scottish family (13). The recent study has reported that 20 family members were affected in a three consecutive generations in Turkey (15). In the previous report of WSN in a Thai family, the patient reported that only his father was similarly affected, but he did not know whether other paternal family members had similar lesions (6).
The clinical and histopathologic features of WSN in this study are in agreement with prior reports (1, 2, 4-7, 14, 16). WSN may be confused with other oral white lesions including candidiasis, leukoedema, lichen planus (LP), leukoplakia, chronic cheek biting, chemical burns and other congenital or familial disorders such as hereditary benign intraepithelial dyskeratosis (HBID), pachyonychia congenita, Darierís disease, dyskeratosis congenita (1-3, 5, 6, 16). The differential diagnosis among these diseases should be based on family history, concomitant skin lesions, clinical and histological characteristics. Unlike white plaque of WSN which is firmly attached to the underlying tissue, white plaque of pseudomembranous candidiasis can be easily removed leaving erythematous surfaces. Chronic hyperplastic candidiasis can be excluded when no fungal hyphae are encountered in the biopsy specimen, candidal culture is negative, and the lesion is unresponsive to antifungal treatment (1, 2, 14). The lesion of leukoedema disappears upon stretching the mucosa while the lesion of WSN still persists (6). The plaque type of LP should have white keratotic striae at the periphery (1). Furthermore, LP could be largely eliminated because its onset is uncommon in childhood or at birth. Leukoplakia is an unlikely diagnosis in a child with no history of smoking and alcohol consumption. Positive familial history is also against the diagnosis of leukoplakia. Chronic cheek biting and chemical burns can be ruled out by careful history taking, clinical examination and absence of family history. WSN may be confused with HBID, pachyonychia congenita, Darierís disease, dyskeratosis congenita. The aforementioned disorders have extra-oral lesions (5). Although WSN primarily affects the oral mucosa, several extraoral mucosal sites including nasal, laryngeal, esophageal and anogenital mucosa, but not conjunctival involvement have been documented (1, 3, 12, 13). HBID is endemic in a triracial population in North Carolina. Apart from oral lesions, patients also develop ocular lesions in the bulbar conjunctiva (1, 2, 5, 9). Pachyonychia congenita has palmar and plantar hyperkeratosis, hyperhidrosis and nail abnormalities (1, 3, 5). Skin changes in Darierís disease are more conspicuous than the oral counterpart (9). Dyskeratosis congenita also exhibits extra-oral manifestations such as skin hyperpigmentation, dysplastic nail changes and hematologic problems in addition to oral lesions (5). In addition, biopsy should be performed for definitive diagnosis and to rule out the risk of dysplasia or malignancy.
Once the diagnosis of WSN is established, no treatment is required (6, 8). However, a few reports have shown the efficacy of the treatment with penicillin and tetracycline, although the results were derived from a small cohort of patients (9-11). The beneficial effect of antibiotics in the treatment of WSN may result from the modulation of epithelial keratinization (9, 11). Furthermore, administration of systemic tetracycline therapy in children with developing dentition should be avoided (9). It is important to reassure the patient of the nature of this disorder and follow-up the patient periodically, especially in cancer phobia patients since the lesion seems to be extensive.  However, malignant transformation has never been reported.

 

 

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Conclusions

We described two cases of WSN from a four-generation family. The family history, clinical and histopathologic characteristics should all be taken into account when establishing the diagnosis. Once the diagnosis of WSN is reached, no treatment other than follow-ups is required. It is important to consider WSN in the differential diagnosis of white lesions in children, particularly with the presence of a family history.

 

 

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