style="font-size:15px;"> 2 Erythema multiforme is precipitated mostly by a previous Herpes virus infection in the majority (>70%) of cases. Both HSV 1 and 2, Epstein‐Barr, varicella zoster and cytomegalovirus DNA fragments trigger autoreactive T cells which via an inflammatory cascade release an interferon gamma that plays a crucial role in the development of EM lesions.3 No
4 No
5 No
Comments: Bacterial, viral, fungal, or even parasitic infections have been involved in the pathogenesis of erythema multiforme. Bacterial infections such as diphtheria, streptococcal, legionellosis, leprosy, tuberculosis, or syphilis have been considered as triggering erythema multiforme. Infections from adenovirus, Coxsackie B5, enteroviruses, influenza, Herpes simplex virus (HSV), measles and mumps viruses or rare fungi such as Histoplasma, Coccidioides immitis and parasites such as Toxoplasma gondii and various species of Trichomonas often precede EM.
Q3 Which blood tests are abnormal in EM patients?
1 White blood account
2 Erythrocyte sedimentation rate (ESR)
3 Blood urea and creatinine
4 Electrolytes
5 Liver enzyme levels
Answers:
1 White blood count usually reveals moderate leukocytosis with atypical lymphocytes and lymphopenia but occasionally eosinophilia. Neutropenia is an indicator of bad prognosis.
2 ESR is an indicator of inflammation and can be elevated.
3 Blood urea and creatinine abnormalities are indicators of renal involvement and seen in severe cases with EM.
4 Electrolyte values are abnormal in severe cases of EM where fluid uptake could be extremely difficult, as it is hard for the patients to drink because of their mouth ulcerations.
5 No
Comments: None of these tests is pathognomonic for the disease and may be abnormal in severe cases. Specifically, the liver enzymes such as aspartate transaminase (AST), alanine transferase (ALT), alkaline phosphatase, and bilirubin are within the normal range in the majority but show an increased tendency in patients with EM due to acute hepatitis or due to antiviral treatment for HIV infection.
Case 2.4
CO: A 72‐year‐old man presented complaining of a black coating on the dorsum of his tongue.
HPC: His black tongue appeared after one week of wide spectrum antibiotic uptake for an upper respiratory infection. This black discoloration appeared suddenly and became daily more dense during treatment. It was associated with mild xerostomia caused by his mouth breathing, and with metallic taste.
PMH: He was suffering from chronic sinusitis, mild hypertension and prostate hypertrophy that were controlled with antibiotics, irbesartan, and tamsulosin tablets respectively. He was an ex‐smoker (stopped smoking eight years ago) and non‐drinker, but used strong mouthwashes on a daily basis.
OE: On examination, black hairy projections on the middle and posterior third of the dorsum of his tongue were seen, but the tip and lateral margins were clear (Figure 2.4). No other lesions were found within his mouth apart from cervical lymphadenopathy which was attributed to his previous upper respiratory infection. The black discoloration was not completely removed by scrubbing with a spatula.
Q1 Which is the possible diagnosis?
1 Hairy black tongue
2 Hairy oral leukoplakia
3 Tongue staining from colored foods
4 Racial pigmentation of tongue
5 Metal poisoning
Answers:
1 Black hairy tongue or lingua villosa nigra is a rare benign tongue condition characterized by elongation of filiform papillae where chromogenic bacteria grow. Poor oral hygiene, black stains from smoking, alcohol, or foods, hyposalivation and antibiotic intake capable to grow for anaerobic chromohenic bacteria or even excessive use of chlorhexidine mouth washes daily are among the possible causes for this condition.
2 No
3 No
4 No
5 No
Comments: Other conditions such as hairy leukoplakia, racial discoloration or that caused by colored foods or metal intake are easily excluded from the black hairy tongue case due to their differences in clinical characteristics such as the color and location, presence of similar or no lesions in the mouth, persistence with scrubbing as well as the patient's history of drug intake or habits. Therefore, in hairy leukoplakia, the lesions are white and usually located on the lateral margins of the tongue, while in racial pigmentation the lesions are located all over the mouth. The dark discoloration caused by colored foods is easily removed with scrubbing, while it remains fixed in metal poisoning and associated with general toxicity symptoms.
Q2 In which other tissues or organs, apart from the tongue, can chromogenic bacteria cause discoloration?
1 Bones
2 Teeth
3 Sclera
4 Skin
5 Heart
Answers:
1 No
2 Chromogenic bacteria in the mouth are responsible for the dark black linear stain that is seen on the cervical part of all teeth (deciduous and permanent) following the contour of gingivae. This stain comes from the deposition of insoluble ferric salts that are produced from the interaction of hydrogen sulfide released from chromogenic bacteria with iron, which is found in the saliva or gingival exudate.
3 No
4 No
5 No
Comments: Discoloration of bones and soft tissues of the skin, heart, and sclera of the eyes are caused by a number of local and systemic causes including trauma, metabolic diseases, tumors (de novo or metastatic) and metals or drugs such as minocycline deposition.
Q3 Which of the bacteria below is the most predominant in dark teeth stains?
Porphyromonas
