4 Bacterial, Viral, Fungal, and Other Infectious Conditions
Any infection that occurs in any other part of the body may manifest in the mouth, including mycobacterial, treponemal, and bartonellal infections, although they are uncommon and rarely occur initially in the mouth. In many parts of the world, mycobacterial and syphilitic infections are on the rise. Polymicrobial bacterial infections in the mouth are the most common and are generally not subject to biopsy because most of these are related to dental caries and periodontal infections. Actinomycosis is one bacterial infection that is seen on biopsy with some frequency.
There are five common areas of involvement—cervical-facial, pulmonary, ileocecal, genitourinary, and central nervous system. The less well known and yet fairly common infection involving the jawbones and oral soft tissues is discussed here.
• Actinomycosis most often manifests as a periapical radiolucency, painful or painless, in a root canal–treated or grossly carious tooth (Fig. 4-1, A); it may also be associated with impacted teeth, periodontitis, or around dental implants; 80% of cases are asymptomatic; approximately 20% involve the soft tissues only; mandibular tooth infection may lead to cutaneous fistula (see Fig. 4-1, B).
Actinomyces are gram-positive microaerophilic, obligate, or facultative filamentous bacteria. There are several species, such as A. odontolyticus, A. israelii, A. naeslundii, A. gerencseriae, and A. viscosus. They cause suppurative lesions and enter the bone through a preexisting sinus tract or through a carious tooth.
• Abundant granulation tissue with abscesses, chronic inflammation; masses of sulfur granules are composed of a round-to-ovoid masses of filamentous bacteria with a peripheral eosinophilic rim often with eosinophilic radiating “clubs” or fringe and clinging neutrophils (Figs. 4-2, 4-3, A-C); bacteria gram-positive and argyrophilic (see Fig. 4-3, D, E); concomitant apical radicular or dentigerous cyst or periapical granuloma often present
FIGURE 4-3 Periapical actinomycosis. A, Periapical granuloma and sulfur granule. B, Sulfur granule with typical radiating morphology and suppuration. C, Sulfur granule (Brown and Brenn stain). D, Sulfur granule containing numerous gram-positive filamentous bacteria. E, Sulfur granule containing slender argyrophilic filaments (methenamine silver stain).
Kaplan I, Anavi K, Anavi Y, et al. The clinical spectrum of Actinomyces-associated lesions of the oral mucosa and jawbones: correlations with histomorphometric analysis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2009;108:738-746.
Ozgursoy OB, Kemal O, Saatci MR, Tulunay O. Actinomycosis in the etiology of recurrent tonsillitis and obstructive tonsillar hypertrophy: answer from a histopathologic point of view. J Otolaryngol Head Neck Surg. 2008;37:865-869.
Tang G, Samaranayake LP, Yip HK, et al. Direct detection of Actinomyces spp. from infected root canals in a Chinese population: a study using PCR-based, oligonucleotide-DNA hybridization technique. J Dent. 2003;31:559-568.
• Angular cheilitis: pain, cracking, fissuring, and maceration of corners of mouth (usually bilateral); seen in denture wearers where dentures do not adequately support soft tissues; also in vitamin B12 and iron deficiencies (see Fig. 4-4, E)
• Hyperplastic candidiasis: white plaques seen in mucocutaneous disease, endocrinopathies, and immunosuppression; common on the commissures bilaterally; often associated with hairy leukoplakia (see later)
FIGURE 4-4 A, Pseudomembranous candidiasis: white plaques and erythema. B, Pseudomembranous candidiasis: lesion in A scrapes off. C, Erythematous candidiasis: erythema in the outline of denture. D, Erythematous candidiasis: same patient as in C after treatment with nystatin and triamcinolone paste applied to denture. E, Angular cheilitis. F, Median rhomboid glossitis. G, Candidiasis presenting as “kissing lesion” on the tongue dorsum. H, Same patient as in G with palatal candidiasis.
Lesions are caused by Candida albicans or other species when the flora in the mouth is altered because of hyposalivation, use of antibiotics or corticosteroids, and immunosuppression. Because Candida is a commensal in approximately 20% of the population, a positive culture in and of itself is not diagnostic for candidiasis. Scraping the lesion and use of either potassium hydroxide or standard cytology stains to identify hyphae is diagnostic, as is a biopsy.
• Epithelial hyperplasia (often psoriasiform) with parakeratosis, neutrophilic exocytosis and spongiotic pustules, reactive epithelial atypia, vascular ectasia, and variable lymphocytic infiltrates (Fig. 4-5, A-C); candidal hyphae and/or conidia seen in the periodic acid–Schiff (PAS) stain with diastase digestion or methenamine silver stain (see Fig. 4-5, A inset); possible epithelial atrophy noted (Fig. 4-6)
FIGURE 4-5 Candidiasis. A, Psoriasiform epithelial hyperplasia with chronic inflammation; periodic acid–Schiff (PAS) stain with diastase reveals candidal hyphae (inset). B, Mild reactive epithelial atypia. C, Neutrophilic exocytosis and early spongiotic pustules.
FIGURE 4-6 Candidiasis. A, Epithelial atrophy, spongiotic pustules, and chronic inflammation; periodic acid–Schiff (PAS) stain with diastase reveals candidal hyphae (inset). B, Reactive epithelial atypia with multinucleated epithelial cells.
• Epithelial dysplasia with secondary candidiasis exhibits significant epithelial atypia and may be difficult to differentiate from candidiasis with reactive atypia (see Fig. 4-6, B); however, effective treatment completely resolves candidiasis without dysplasia.
Pienaar ED, Young T, Holmes H. Interventions for the prevention and management of oropharyngeal candidiasis associated with HIV infection in adults and children. Cochrane Database Syst Rev. 2010;11:CD003940.
Infectious Granulomatous Inflammation
• Ulcerated and indurated, granular, vegetating nodules of the palate and gingiva are common oral presentations, and there is usually concomitant lung, nodal, and skin disease; immunocompromised patients are particularly susceptible to disseminated disease.
• Histoplasmosis caused by Histoplasma capsulatum is endemic to the Ohio-Mississippi Valley and is found in the soil and in bird and bat droppings; patients taking tumor necrosis factor-α inhibitors are prone to contracting this infection, as well as coccidioidomycosis in endemic areas.
• Phycomycoses (order Mucorales, genera Rhizopus, Absidia, Mucor, and Rhizomucor) and aspergillosis (Aspergillus fumigatum or A. flavus) appear black, necrotic and/or fungating, resembling malignancy; rhinocerebral phycomycosis is increasing in frequency and is often seen in patients with diabetes (especially if ketoacidotic), neutropenia, malignancy, and post–organ transplantation; mortality rate is 60% to 90%; aspergillosis appears similar but tends to affect immunocompromised patients (such as those with leukemia) rather than those with diabetes; both primarily affect the palate and maxilla, and vascular involvement leads to necrosis.
• Aspergillosis is similar to zygomycosis but organisms are slender and show acute-angle branching (Fig. 4-12); must be differentiated from mycetoma or “fungus ball” within the sinus that does not invade the soft tissues (Fig. 4-13).
FIGURE 4-9 Oral coccidioidomycosis. A, Pseudoepitheliomatous hyperplasia and granulomatous inflammation within the muscle. B, Necrotizing granulomatous inflammation with many coccidioidal spherules. C, Granulomas with large spherules containing hundreds of endospores.
(A, Courtesy of Dr. Roman Carlos, Guatemala.)