Case Report: Scabies Invading Gingival Tissue

INTRODUCTION

Non–plaque-induced pathologic lesions may occur on the gingiva as medical disorders or manifestations of systemic conditions. ¹ A recent review published in 2017 presents a classification of these most relevant diseases, including immune disorders, infections, and other conditions. Among infections reported, fungal, viral, and bacterial origins are described, and parasitic diseases were not included. ¹

Scabies is a parasitic infestation caused by the mite Sarcoptes scabiei. It is a common disease, especially in areas with poor hygiene, and could be transmitted through close personal contact. ^2,3 The classic sites of affection are on the skin such as the wrists, between the fingers, axillary areas, female breasts (especially the nipple skin), periumbilical area, penis, scrotum, and buttocks. ⁴ Interestingly, we did not find oral scabies cases in the English literature.

Based on this, here, we report a rare case of oral scabies located on the gingiva, highlighting the difficulties of this diagnosis, especially when a presumptive diagnosis was made. This report follows the Case Report Guidelines. ⁵

CASE REPORT

A 43-year-old woman, Caucasian, looked for our diagnostic service complaining of an ulcerative lesion on both gingivae with unknown duration. She looked for us with a clinical and suggestive microscopic diagnosis of pemphigoid and underwent daily 20 mg prednisone for many months without resolution or clinical improvement. The patient was feverless and normotensive and was not immunocompromised but reported concomitant rheumatic fever, vitiligo, and psoriasis histories during anamnesis. She also referred to be submitted to different treatments and to manage the gingival disease, such as diet care and topical ointments without healing or resolution.

During the extraoral examination, we also observed ulcerative and crusty lesions on the hands, feet, and chin, and vitiligo manifestations (Figure 1A–C). Panoramic radiographic examination of the oral region showed no alterations. Curiously, she cited a synchronous presentation of the gingival lesion with painful and itching alterations on the hands, feet, and chin lesions. During the report, she said to us when squeezed the skin of limbs, a brownish substance was released and even various mitis could be observed. We asked her about contact with ill animals, she confirmed an indirect association, citing a relative of her husband who works rescuing abandoned animals on the street. On intraoral examination, we noted an ulcerative and granular lesion affecting anterior marginal gingival tissue on both arches (Figure 1D). We asked for a slide review of this previous biopsy. During that time, we asked ourselves about the possibility of an infectious process affecting gingival tissue and its association with other clinical manifestations. Of course, we thought about scabies infestation, but we did not find consistent reports on the literature focusing on its oral manifestation.

View Full Size

(A–D) Ulcerative and granular lesions affecting anterior marginal gingival tissue on both arch and crusty lesions on the hands, feet, and chin and vitiligo manifestations. (E–H) Healed skin and mucosal lesions 30 days after completion of therapy.

Citation: The American Journal of Tropical Medicine and Hygiene 104, 1; 10.4269/ajtmh.20-0707

• Download Figure
• Download figure as PowerPoint slide

To conduct our diagnosis, we performed exfoliative cytology on the gingival tissue, while we were waiting for the original slide review. On panoptic staining, we observed an intense inflammatory infiltrate, eggs, and larva/nymph forms which characterized an oral scabies infestation (Figure 2A–B). During the slide review, a misinterpretation of the subepithelial cleft as suggestive of pemphigoid was perceived, and scabies feces, eggs, and bristles were identified corroborating the scabies infestation diagnosis on the gingival tissue with a good prognosis (Figure 2C–D). After diagnosis, 100 mg of ivermectin was given orally three times per day for 15 days. We also prescribed supplemental oral hygiene with chlorhexidine mouthwash, and the patient was instructed to make extensive cleaning, disinfection, and laundering of the bed, bedroom, bedding, and clothing. The follow-up was conducted 30 days after treatment with ivermectin. The patient did not report side effects, with skin and oral lesions completely healed (Figure 1E–H). We inferred that oral lesions could be associated with direct contact with finger lesions because of itching symptoms.

View Full Size

(A–B) Cytological smear revealing inflammatory infiltrates, larvae/nymphs, dorsal surface structures, and eggs. (C–D) Histological features revealed scabies feces, eggs, and bristles.

Citation: The American Journal of Tropical Medicine and Hygiene 104, 1; 10.4269/ajtmh.20-0707

• Download Figure
• Download figure as PowerPoint slide

DISCUSSION

This report shows the first case of oral scabies reported in the literature located on the gingiva in a patient with a presumptive diagnosis of pemphigoid without improvement. Scabies is a parasitic skin infection caused by the mite called S. scabiei and is considered a public health problem, with an estimated prevalence of 300 million cases. ^6,7 It is more frequent in areas with poor sanitation and overcrowding and is endemic in some tropical countries, which can be seen in the present case diagnosed in Northeastern Brazil. ^6,7

Humans are the main reservoirs of S. scabiei var. hominis (subtype named to reflect the main host species) and are generally transmitted from person to person by direct contact with the skin, including sexual contact, although less frequently it can be through inanimate objects, such as clothes and furniture. ⁴ Interestingly, the patient reported that a relative of her husband works rescuing abandoned animals on the street, and this may have been the route of transmission.

Initially, the possibility of mucous membrane pemphigoid (MMP) was ruled out, as the physical examination did not reveal a history of blisters on the body, eye damage, and Nikolsky’s sign, clinical features of MMP. ⁸ However, even during the physical examination, the presence of simultaneous lesions on the skin with insects exiting while rubbing and the history of indirect contact with sick animals strongly suspected an infestation. A search of the literature on scabies was made, with similar clinical manifestation had not yet been reported in the oral cavity. Therefore, the suggested hypothesis was an infectious lesion with the possibility of being oral scabies.

Although there are some national guidelines regarding the diagnosis, there are no internationally agreed standards. ⁹ Among the methods adopted, the presence of 10–15 adult female mites is required in classical infestations, and their identification is pathognomonic but may not be present or demonstrable in all cases. ^9,10 The gold standard of diagnosis is the demonstration of live mites, eggs, or fecal material through skin scraping methods. However, this test requires microscopy and is not always practicable in all clinical contexts. ^9,10 In our case, through exfoliative cytology in the oral cavity associated with an incisional biopsy, an intense inflammatory infiltrate was observed being associated with eggs and larvae, which confirmed the diagnosis of scabies in an unusual location, which includes the oral cavity as an anatomical site of involvement.

The ideal management to scabies control it is the treatment of people with symptoms and their domestic contacts. Despite this, longitudinal data are scarce to suggest a possible reduction in prevalence, and reinfestation is common in endemic environments. ¹¹ Furthermore, scabies has several effective options, and ivermectin (topical or systemic) and permethrin (topical) have high clearance rates. ⁴ In our case, 100 mg of systemic ivermectin (three times per day for 15 days) was chosen in addition to mouthwash with 0.1% chlorhexidine digluconate prescription and cleaning and disinfecting clothes and residence. The treatment performed obtained positive results, and there was complete remission of the lesions in the mouth after 45 days of treatment.

CONCLUSION

We can learn many important things in this case. Primarily, when examining patients with gingival lesions who are not responding to conventional treatments, we need to be alert to signs that indicate unusual causes, even if they come with some pre-established diagnosis. Performing a thoughtful ectoscopy examination and correlating the signs and symptoms presenting in the entire body with the medical history will allow managing properly the diagnosis and choosing appropriate treatment.