What are the other Names for this Condition? (Also known as/Synonyms)

• Cat Scratch Disease causing Enlarged Lymph Nodes
• Cat Scratch Disease Lymphadenitis
• Enlarged Lymph Nodes due to Cat Scratch Disease

What is Cat Scratch Disease Lymphadenopathy? (Definition/Background Information)

• Cat Scratch Disease Lymphadenopathy is the inflammation and enlargement of lymph nodes due to underlying Cat Scratch Disease, which is caused by a bacterium
• Cat Scratch Disease is an infection caused by Bartonella henselae bacteria. It is transmitted to humans through contact with infected cats, through their bites, licks, or scratches, since the bacteria is found in the saliva and claws of cats and kittens
• The signs and symptoms of Cat Scratch Disease Lymphadenopathy include enlarged lymph nodes (around the bite/scratch site) that are not painful. After contact with the infected animal, the contact site may become sore, following which fever, body ache, headache, and malaise may occur
• Healthy individuals with a strong immune system generally overcome Cat Scratch Disease and symptomatic treatment may be provided. The prognosis of Cat Scratch Disease Lymphadenopathy generally depends upon the severity of the underlying signs and symptoms due to the bacterial infection

General information on lymph nodes:

The lymph nodes are part of one’s immune system. The lymph nodes are present throughout the body, usually in groups. In normal healthy adults, one cannot feel (see or touch) the lymph nodes readily. However, if they are enlarged, they can be felt either by the individual himself/herself or by the healthcare provider.

Enlarged lymph nodes can occur in both benign and malignant conditions. Hence, the cause of enlarged lymph nodes should be evaluated. If no obvious cause for enlargement of lymph nodes is found, then the possibility of a lymph node malignancy should be ruled out.

In a majority of individuals, a lymph node swelling is caused by a benign process such as inflammation or infection. In many cases, swollen lymph nodes are part of other signs and symptoms. This can help a healthcare provider arrive at a list of follow-up tests and ensure an accurate diagnosis. Superficial enlarged lymph nodes can be felt by the healthcare provider through palpation. Enlarged lymph nodes deep in the body are often detected by radiological studies such as X-rays, ultrasound scan, CT and MRI scans.

Some enlarged lymph nodes can be painful, while others may be painless. Depending upon the underlying cause, enlarged lymph nodes can be localized to a particular area of the body, or they can be generalized, meaning that they are present throughout the body.

Who gets Cat Scratch Disease Lymphadenopathy? (Age and Sex Distribution)

• Cat Scratch Disease Lymphadenopathy occurs due to underlying Cat Scratch Disease. Individuals of any age are prone to the infection
• However, the condition is common among children and teenagers, especially because they are likely to play more with cats
• Cat Scratch Disease is slightly more common in males than in females
• The disease is seen worldwide, especially in the hot and humid regions. It can affect individuals of any race or ethnicity

What are the Risk Factors for Cat Scratch Disease Lymphadenopathy? (Predisposing Factors)

The main risk factor for Cat Scratch Disease Lymphadenopathy is the underlying Cat Scratch Disease. The risk factors for Cat Scratch Disease include:

• Playing with or petting infected cats or kittens
• Exposure to kittens rather than cats, places an individual at a much greater risk (about 15 times higher risk) 
• Areas where the climate is warm and humid, which favor flea population (fleas carry the bacteria from cat to cat through bites). It has been speculated that fleas may carry the Bartonella bacteria directly to humans who present with the disease in the absence of contact with cats
• People living in regions where fleas are endemic are at increased risk
• Immunocompromised individuals, such as those with HIV infection, organ transplant patients, or those getting cancer chemotherapy have a higher chance of being affected

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Cat Scratch Disease Lymphadenopathy? (Etiology)

Cat Scratch Disease Lymphadenopathy is caused by Bartonella henselae, which is found in the saliva of cats and kittens. These bacteria are transmitted to humans through contact with infected cats and kittens.

The transmission of the bacteria to humans, resulting in Cat Scratch Disease, may occur in the following ways:

• Cat scratch: The bacteria may be present in its claws 
• Cat bite or lick: The bacteria may be present in its oral cavity or saliva
• Petting cats: The bacteria may also be present in the cat’s fur and get transferred to the hands. From the hands, the bacteria can enter into any part of the body through actions such as rubbing one’s eyes with the same hand, eating a snack without washing the hands, etc.
• Sometimes, dogs and thorn pricks can also be sources of infection, but these are very uncommon

What are the Signs and Symptoms of Cat Scratch Disease Lymphadenopathy?

The signs and symptoms of Cat Scratch Disease Lymphadenopathy may include:

• Lymphadenopathy or (swollen lymph nodes) that occur in the armpits, head, neck, and groin region
• The lymph nodes closest to the bite or scratch site gets enlarged, 1-3 weeks after the bite/scratch occurs
• Lymphadenopathy usually involves only one side of the body (near the site of the bite/scratch)
• In over half the cases, enlargement of the lymph nodes may be seen

In general, the signs and symptoms of Cat Scratch Disease are grouped as typical and atypical. They  differ as outlined below:

The signs and symptoms for Typical (Classical) Cat Scratch Disease are usually mild and they may include:

• In most of the cases (95% of them), individuals with the disease usually have a history of exposure to cats
• A red patch develops in 1 to 3 weeks following exposure to the infected cat. This is called an inoculation lesion. It then becomes a bump, which may develop pus formation, and then break open, finally ending up as a scar
• Enlarged lymph nodes
• Lethargy, malaise
• Flu-like symptoms such as body aches, headache, and fever

The signs and symptoms for Atypical Cat Scratch Disease are uncommon. Usually, when individuals present with atypical disease, they may appear to have some signs and symptoms of the typical disease. Sometimes, they may present only with symptoms specific to the atypical disease, and these include:

• Loss of appetite or poor appetite, weight loss
• Backache, joint pain
• Abdominal pain
• Formation of skin rashes
• High fever, sweats, and chills
• Vomiting
• Sore throat
• Fits (seizures)
• Enlargement of the spleen
• Pericarditis (inflammation of the lining outside the heart)
• Pleural effusion (fluid around the lungs) 
• Bone lesions: In children, bones lesions (osteolytic) and inflammation of the liver and spleen may also be seen

Some serious and rare, signs and symptoms of Cat Scratch Disease based on the organs affected include:

• Bacillary angiomatosis: Skin lesions (red, elevated bumps surrounded by a scaly ring) and spread of the disease to deeper and other areas of the body such as the bone
• Parinaud’s Oculoglandular Syndrome that is characterized by pink eye in one eye only, fever, and swelling of the lymph nodes in front of the ear (preauricular lymphadenopathy) on the same side as the conjunctivitis
• Optic neuritis: Infection of the retina (inner part of the eye)
• Encephalopathy or inflammation of the brain can occur in immunocompromised individuals. There is usually no negative sequelae

How is Cat Scratch Disease Lymphadenopathy Diagnosed?

The diagnosis of Cat Scratch Disease Lymphadenopathy may involve the following tests and exams:

• Thorough evaluation of the individual’s medical history and a complete physical examination, including examination of the skin
• During history taking, the physician may want to know the following:
  • When the symptoms began and whether they are becoming worse
  • Any history of exposure to cats, kittens, or dogs (including if the individual walked barefoot outdoors recently)
• A physical examination may reveal a cat scratch or bite on the skin, swollen lymph nodes, and an enlarged spleen. History and physical exam may suggest a diagnosis of Cat Scratch Disease Lymphadenopathy
• Sometimes, the diagnosis may be difficult with only a history and physical exam, especially when there is no history of exposure to cats or kittens
• Indirect fluorescent antibody test (IFA) for Bartonella henselae is a screening (blood) test for Cat Scratch Disease. However, the test cannot always differentiate between an active infection or a past infection. Antibody titers are higher in new or very recent infection. Also, in early infections, IgM class immunoglobulins are present, as they are the ‘initial responder’ class of antibodies 
• Blood culture followed by polymerase chain reaction (PCR) for detection of Bartonella henselae is the most definitive test for Cat Scratch Disease
• Electron microscopy, in rare cases
• Lymph node biopsy may be done to rule-out other causes of swollen glands (such as a lymphoma). It is not used as the primary test for Cat Scratch Disease Lymphadenopathy

In case a lymph node biopsy is performed.

• Lymph node biopsy: A lymph node biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. The pathologist may use special techniques, such as immunohistochemistry stains, to help reveal the presence of the pathogen
• The lymph node biopsy may be performed through any of the following procedures:
  • Fine needle aspiration biopsy (FNAB): A device called a cannula is used to extract tissue or fluid from the lymph nodes
  • Lymph node core biopsy of the enlarged lymph node
  • Lymph node open biopsy of the enlarged lymph node

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Cat Scratch Disease Lymphadenopathy?

Generally, Cat Scratch Disease causing Lymphadenopathy does not lead to any complications. However, an immune compromised individual may be more susceptible to complications of Cat Scratch Disease that may include:

• Encephalopathy: Inflammation of the brain
• Endocarditis: Inflammation and infection of the inner lining of the heart chambers and valves
• Osteomyelitis: Infection of the bone
• Optic neuroretinitis: Inflammation and/or infection of the optic nerve and retina
• Hepatitis: Inflammation of the liver that may cause abdominal pain

How is Cat Scratch Disease Lymphadenopathy Treated?

Cat Scratch Disease Lymphadenopathy is usually a mild disease and symptomatic treatment may suffice for most individuals. A spontaneous resolution of the condition may also take place in individuals with a healthy immune system.

The treatment options available may include:

• For mild and moderate disease, local heat application to reduce the swelling of the lymph nodes and medications for fever and pain are sufficient
• Lymph node aspiration with needle is sometimes performed to relieve pain in the lymph nodes. Incision and drainage of lymph nodes is generally not recommended, because it may result in scarring and fistulae formation (abnormal opening to the skin from deeper parts), which may lead to secondary infections

Note: It is very important to note that the enlarged lymph node may remain for several months, even after other signs and symptoms of the infection disappear.

• For severe cases of Cat Scratch Disease and for immune-compromised individuals, antibiotics such as azithromycin, rifampin, clarithromycin, ciprofloxacin, gentamicin, or trimethoprim-sulfamethoxazole, doxycycline, or erythromycin, may be prescribed, alone or in combination

The healthcare provider will recommend the best treatment options based on a case-by-case consideration.

How can Cat Scratch Disease Lymphadenopathy be Prevented?

The preventative measures for Cat Scratch Disease Lymphadenopathy includes reducing the risk of Bartonella henselae transmission from cats. Also, currently, there is no vaccine to prevent Cat Scratch Disease. The following measures are useful in controlling transmission of the condition:

• Avoiding petting methods that may make the cats and kittens aggressive to the extent that they end up scratching or biting
• Play cautiously with cats and kittens while ensuring that they do not lick the face, areas around the eyes, or any skin wound
• Ensuring that the cats are free from fleas
• Immediately washing any scratch, licks, or bites of cats and kittens with running water and soap

What is the Prognosis of Cat Scratch Disease Lymphadenopathy? (Outcomes/Resolutions)

The prognosis of Cat Scratch Disease Lymphadenopathy is based on the severity of the underlying Cat Scratch Disease infection.

• The prognosis of underlying Cat Scratch Disease is generally good for both healthy and immunocompromised individuals. Complications are also very rare in normal, healthy individuals
• Many a times, the condition gets better on its own even without treatment in individuals with good immune system
• Immune-compromised individuals usually recover fully with proper antibiotic treatment, though it may take them longer

Additional and Relevant Useful Information for Cat Scratch Disease Lymphadenopathy:

• Bacillary angiomatosis is caused by the bacterium Bartonella henselea or Bartonella quintana in individuals with poor immune system

The following article link will help you understand bacillary angiomatosis:

https://www.dovemed.com/diseases-conditions/bacillary-angiomatosis/