Pharyngitis differential diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Venkata Sivakrishna Kumar Pulivarthi M.B.B.S [2]

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Overview

Pharyngitis should be differentiated from other infectious causes which mimic sore throat that includes oral thrush, infectious mononucleosis, epiglottitis and retropharyngeal abscess.

Differentiating Pharyngitis from other Diseases

The major goal of the differentiating patients with sore throat or acute pharyngitis is to exclude potentially dangerous causes (e.g. Group A streptococcus), to identify any treatable causes, and to improve symptoms. Identifying the treatable causes is important because timely treatment with antibiotics helps prevent complications such as acute rheumatic fever, post-streptococcal glomerulonephritis.

Disease/Variable	Presentation	Causes	Physical exams findings	Age commonly affected	Imaging finding	Treatment
Peritonsillar abscess	Severe sore throat, otalgia fever, a "hot potato" or muffled voice, drooling, and trismus	Aerobic and anaerobic bacteria most common is Streptococcus pyogenes.	Contralateral deflection of the uvula, the tonsil is displaced inferiorly and medially, tender submandibular and anterior cervical lymph nodes, tonsillar hypertrophy with likely peritonsillar edema.	The highest occurrence is in adults between 20 to 40 years of age.	On ultrasound peritonsillar abscess appears as focal irregularly marginated hypoechoic area.	Ampicillin-sulbactam, Clindamycin, Vancomycin or Linezolid
Croup	Has cough and stridor but no drooling. Others are Hoarseness, Difficulty breathing, symptoms of the common cold, Runny nose, Fever	Parainfluenza virus	Suprasternal and intercostal indrawing, Inspiratory stridor, expiratory wheezing, Sternal wall retractions	Mainly 6 months and 3 years old rarely, adolescents and adults	Steeple sign on neck X-ray	Dexamethasone and nebulised epinephrine
Epiglottitis	Stridor and drooling but no cough. Other symptoms include difficulty breathing, fever, chills, difficulty swallowing, hoarseness of voice	H. influenza type b, beta-hemolytic streptococci, Staphylococcus aureus, fungi and viruses.	Cyanosis, Cervical lymphadenopathy, Inflamed epiglottis	Used to be mostly found in pediatric age group between 3 to 5 years, however, recent trend favors adults as most commonly affected individuals with a mean age of 44.94 years	Thumbprint sign on neck x-ray	Airway maintenance, parenteral Cefotaxime or Ceftriaxone in combination with Vancomycin. Adjuvant therapy includes corticosteroids and racemic Epinephrine.
Pharyngitis	Sore throat, pain on swallowing, fever, headache, abdominal pain, nausea and vomiting	Group A beta-hemolytic streptococcus.	Inflamed pharynx with or without exudate	Mostly in children and young adults, with 50% of cases identified between the ages of 5 to 24 years	_	Antimicrobial therapy mainly penicillin-based and analgesics.
Tonsilitis	Sore throat, pain on swallowing, fever, headache, and cough	Most common cause is viral including adenovirus, rhinovirus, influenza, coronavirus, and respiratory syncytial virus. Second most common causes are bacterial; Group A streptococcal bacteria	Fever, especially 100°F or higher. Erythema, edema and exudate of the tonsils, cervical lymphadenopathy, and Dysphonia.	Primarily affects children between 5 and 15 years old.	Intraoral or transcutaneous USG may show an abscess making CT scan unnecessary.	Antimicrobial therapy mainly penicillin-based and analgesics with tonsilectomy in selected cases.
Retropharyngeal abscess	Neck pain, stiff neck, torticollis, fever, malaise, stridor, and barking cough	Polymicrobial infection. Mostly; Streptococcus pyogenes, Staphylococcus aureus and respiratory anaerobes (example; Fusobacteria, Prevotella, and Veillonella species)	Child may be unable to open the mouth widely. May have enlarged cervical lymph nodes and neck mass.	Mostly between 2-4 years, but can occur in other age groups.	On CT scan, a mass impinging on the posterior pharyngeal wall with rim enhancement is seen	Immediate surgical drainage and antimicrobial therapy. emperic therapy involves; ampicillin-sulbactam or clindamycin.

The table below summarizes the findings that differentiate pharyngitis from other conditions that cause fever, fatigue, abdominal pain and diarrhea:

Disease	Findings
Ebola	Presents with fever, chills vomiting, diarrhea, generalized pain or malaise, and sometimes internal and external bleeding, that follow an incubation period of 2-21 days.
Typhoid fever	Presents with fever, headache, rash, gastrointestinal symptoms, with lymphadenopathy, relative bradycardia, cough and leucopenia and sometimes sore throat. Blood and stool culture can confirm the presence of the causative bacteria.
Malaria	Presents with acute fever, headache and sometimes diarrhea (children). A blood smears must be examined for malaria parasites. The presence of parasites does not exclude a concurrent viral infection. An antimalarial should be prescribed as an empiric therapy.
Lassa fever	Disease onset is usually gradual, with fever, sore throat, cough, pharyngitis, and facial edema in the later stages. Inflammation and exudation of the pharynx and conjunctiva are common.
Yellow fever and other Flaviviridae	Present with hemorrhagic complications. Epidemiological investigation may reveal a pattern of disease transmission by an insect vector. Virus isolation and serological investigation serves to distinguish these viruses. Confirmed history of previous yellow fever vaccination will rule out yellow fever.
Shigellosis & other bacterial enteric infections	Presents with diarrhea, possibly bloody, accompanied by fever, nausea, and sometimes toxemia, vomiting, cramps, and tenesmus. Stools contain blood and mucous in a typical case. A search for possible sites of bacterial infection, together with cultures and blood smears, should be made. Presence of leucocytosis distinguishes bacterial infections from viral infections.
Leukemia	Cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms.
Tonsillitis	Tonsillitis is characterized by signs of red, swollen tonsils which may have a purulent exudative coating of white patches (i.e. pus). In addition, there may be enlarged and tender neck cervical lymph nodes.
Pharyngitis	Typically characterized by sore throat, but commonly accompanied by fever, headache, joint pain and muscle aches, skin rashes, swollen lymph nodes in the neck, diphtheria and common cold.
Adenovirus infections	Commonly presents by a cold syndrome, pneumonia, croup and bronchitis.
Influenza	Symptoms of influenza can start quite suddenly one to two days after infection. Usually the first symptoms are chills or a chilly sensation but fever is also common early in the infection, with body temperatures as high as 39 °C (approximately 103 °F). Many people are so ill that they are confined to bed for several days, with aches and pains throughout their bodies, which are worst in their backs and legs. Common symptoms of the flu such as fever, headaches, and fatigue come from the huge amounts of proinflammatory cytokines and chemokines (such as interferon or tumor necrosis factor) produced from influenza-infected cells. In contrast to the rhinovirus that causes the common cold, influenza does cause tissue damage, so symptoms are not entirely due to the inflammatory response.
Others	Leptospirosis, rheumatic fever, typhus, and mononucleosis can produce signs and symptoms that may be confused with Ebola in the early stages of infection.

The table below summarizes the findings that differentiate influenza from other conditions that cause fever, fatigue, abdominal pain and diarrhea:

Disease	Findings
Ebola	Presents with fever, chills vomiting, diarrhea, generalized pain or malaise, and sometimes internal and external bleeding, that follow an incubation period of 2-21 days.
Typhoid fever	Presents with fever, headache, rash, gastrointestinal symptoms, with lymphadenopathy, relative bradycardia, cough and leucopenia and sometimes sore throat. Blood and stool culture can confirm the presence of the causative bacteria.
Malaria	Presents with acute fever, headache and sometimes diarrhea (children). A blood smears must be examined for malaria parasites. The presence of parasites does not exclude a concurrent viral infection. An antimalarial should be prescribed as an empiric therapy.
Lassa fever	Disease onset is usually gradual, with fever, sore throat, cough, pharyngitis, and facial edema in the later stages. Inflammation and exudation of the pharynx and conjunctiva are common.
Yellow fever and other Flaviviridae	Present with hemorrhagic complications. Epidemiological investigation may reveal a pattern of disease transmission by an insect vector. Virus isolation and serological investigation serves to distinguish these viruses. Confirmed history of previous yellow fever vaccination will rule out yellow fever.
Shigellosis & other bacterial enteric infections	Presents with diarrhea, possibly bloody, accompanied by fever, nausea, and sometimes toxemia, vomiting, cramps, and tenesmus. Stools contain blood and mucous in a typical case. A search for possible sites of bacterial infection, together with cultures and blood smears, should be made. Presence of leucocytosis distinguishes bacterial infections from viral infections.
Leukemia	Cancer of the blood or bone marrow and is characterized by an abnormal proliferation (production by multiplication) of blood cells, usually white blood cells (leukocytes). It is part of the broad group of diseases called hematological neoplasms.
Tonsillitis	Tonsillitis is characterized by signs of red, swollen tonsils which may have a purulent exudative coating of white patches (i.e. pus). In addition, there may be enlarged and tender neck cervical lymph nodes.
Pharyngitis	Typically characterized by sore throat, but commonly accompanied by fever, headache, joint pain and muscle aches, skin rashes, swollen lymph nodes in the neck, diphtheria and common cold.
Adenovirus infections	Commonly presents by a cold syndrome, pneumonia, croup and bronchitis.
Influenza	Symptoms of influenza can start quite suddenly one to two days after infection. Usually the first symptoms are chills or a chilly sensation but fever is also common early in the infection, with body temperatures as high as 39 °C (approximately 103 °F). Many people are so ill that they are confined to bed for several days, with aches and pains throughout their bodies, which are worst in their backs and legs. Common symptoms of the flu such as fever, headaches, and fatigue come from the huge amounts of proinflammatory cytokines and chemokines (such as interferon or tumor necrosis factor) produced from influenza-infected cells. In contrast to the rhinovirus that causes the common cold, influenza does cause tissue damage, so symptoms are not entirely due to the inflammatory response.
Others	Leptospirosis, rheumatic fever, typhus, and mononucleosis can produce signs and symptoms that may be confused with Ebola in the early stages of infection.