Rare forms of diphtheria

Instrumental methods and their role

When suspicious fibrinous plaques are detected, rhinoscopy, laryngoscopy, and bronchoscopy are used as additional diagnostic methods.

The primary goal of these interventions is to precisely determine the extent of the pathological process. Visualization of the airways provides an opportunity to objectively assess the degree of obstruction and the severity of stenosis, which is necessary to determine the severity of laryngeal diphtheria and select further patient management tactics.

Differential diagnosis of oropharyngeal lesions

In localized and generalized forms, diphtheria must be differentiated from a number of infectious diseases accompanied by tonsillitis.

• Follicular and lacunar tonsillitis (staphylococcal and streptococcal): Characterized by a complete correlation between the severity of local inflammation and general intoxication. Unlike diphtheria, there is no edema of the oropharyngeal mucosa and tonsils, and their structure is intact. The plaque in the lacunae has a sour-cream consistency, does not rise above the epithelium, is easily removed with a spatula without leaving bleeding erosions. Submandibular lymph nodes are markedly painful.
• Scarlet fever: Characterized by bright, "fiery" mucosal hyperemia with a clear border along the soft palate, the presence of a maculopapular rash, and a pale nasolabial triangle. The general toxic syndrome predominates, lymphadenitis is sharply painful (up to periadenitis).
• Vincent's angina: Manifests as a unilateral, painless crateriform tonsillar necrosis with a dirty greenish plaque and a putrid odor. Regional lymphadenitis is almost unnoticeable.
• Syphilis (secondary): Syphilids in the subpapillary zone may resemble a delicate fibrinous plaque, usually on one tonsil. Intoxication and sore throat are absent, the course is prolonged (weeks). Polyadenitis and hoarseness may develop if the larynx is involved.
• Tularemia (anginal form): Characterized by ulceronecrotic defects and the formation of a large bubo (moderately painful) a few days after disease onset. There is no surrounding tissue edema; blood tests show leukopenia and lymphomonocytosis.

Mimicking toxic forms of diphtheria

Toxic forms of diphtheria, accompanied by pronounced oropharyngeal and neck edema, require differential diagnosis with burns and severe surgical pathology.

Chemical and thermal burns Grayish plaques forming on the burned surface can mimic widespread diphtheria. However, their density and bulkiness never reach the level of diphtheritic fibrin. The anamnesis is of decisive importance, along with the presence of burns in the mouth and esophagus, severe pain, salivation, and dysphagia in the absence of signs of intoxication at onset.

Purulent processes (abscesses and phlegmons)

• Peritonsillar abscess: Pus shining through the thinned mucosa may look like a fibrinous exudate. The pathology develops after inadequately treated tonsillitis, manifesting as unilateral throbbing pain, trismus, and high fever. There is no true plaque. Puncture with pus aspiration resolves any doubts.
• Neck phlegmon and Ludwig's angina (phlegmon of the cellular spaces of the floor of the mouth): Show maximum similarity to toxic diphtheria. Distinctive features are neutrophilic hyperleukocytosis with a sharp left shift, shaking chills and sweats. Neck edema acquires a "woody" density, a purplish-bluish tint, and the patient's condition rapidly deteriorates due to the threat of sepsis and shock.

Laryngeal diphtheria: true and false croup

Laryngeal diphtheria (true croup) is primarily differentiated from "false croup", which develops against the background of acute respiratory viral infections (ARVI), parainfluenza, measles, or pertussis. False croup occurs at the peak of the disease against a background of high fever, develops acutely, and is not accompanied by preceding persistent aphonia. Attacks are successfully relieved by the discharge of mucous sputum and the use of antispasmodics, mucolytics, and sedatives. Laryngoscopy reveals subglottic catarrhal laryngitis.

Other causes of stenosis to be ruled out:

1. Fungal and herpetic infections: Develop gradually against the background of immunosuppression, combine with stomatitis and hypersalivation, and rarely lead to asphyxia.
2. Foreign bodies: Characterized by a sudden attack of suffocation and cough without prior intoxication and without voice changes (often during aspiration in children or individuals with alcoholism).
3. Laryngeal oncology: Differs by a very slow, steady increase in signs of stenosis.
4. Retropharyngeal abscess: Occurs after trauma to the posterior pharyngeal wall (e.g., by a bone) or as a complication of tonsillitis.

Class and exam questions

What else to study on this topic

• Parallelism of local and general symptoms in lacunar tonsillitis
• Hemogram in toxic forms of diphtheria and purulent phlegmons
• Clinical presentation and laryngoscopy in catarrhal subglottic laryngitis
• Differential diagnosis of syphilitic oropharyngeal lesions
• Assessment of stenosis severity in foreign body aspiration

Other topics in the "Respiratory Infections" section

Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.