Infectious Disease Compendium

Lymphadenitis

Diagnosis

Big, tender lymph nodes. They can be regional or diffuse (PubMed).

Normal nodes can be up to 10 mm, depending on location.

The big question is to watch and wait or remove it for diagnosis. That can be a difficult question. A careful exposure and travel history may give a hint as to the cause. I tend to want all or nothing: take out a node, cut it in half with one piece to pathology and the other to microbiology. Fine needle is great for cancer, but I am not so certain as to its utility for infection. The literature for fine needle biopsy is thin for its utility in my world.

Palpable supraclavicular, popliteal, and iliac nodes are abnormal, as are epitrochlear nodes greater than 5 mm in diameter.

And nodes around the belly button? Think of Sister Mary Joseph (PubMed). It's gastric or other gi cancer.

Epidemiologic Risks

It depends on the disease risk.

Microbiology

S. aureus and Group A Streptococci: Acute unilateral cervical lymphadenitis (PubMed) in 40% to 80% of cases. 

Bartonella aka Cat Scratch disease. Often downstream of the scratch. Pathology will show stellate necrotizing granulomas.

EBV.

Yersinia enterocolitica or pseudotuberculosis: Mesenteric lymphadenitis (PubMed) that mimics acute appendicitis.

Toxoplasmosis.

Secondary syphilis.

Tularemia

Typhoid

Brucella

TB and non-Tubercular mycobacterium: aka scrofula or the Kings Touch.

Disseminated TB and endemic fungi (coccidioidomycosis, cryptococcosis, histoplasmosis ) of all kinds.

Part of IRIS and opportunistic infection in AIDS patients.

Adenovirus, cytomegalovirus, herpes zoster, human immunodeficiency virus.

Kikuchi disease: fever, lymphadenopathy, skin rash, and headache. Rarely, enlarged liver and spleen and CNS involvement resembling meningitis.

And more. One of those processes that can be caused by damn near anything.

And a metric tonne of non-infectious causes.

Empiric Therapy

It depends on the suspected cause.

Pearls

Lymph nodes get big fast but go away slowly.

Inguinal nodes are the most useless to biopsy.

Rants

I wish I had a nickel for every infection that was sent my way with the whole node plunked in formalin with nothing sent for culture. At least in this age we have 16S to make up the difference, but still.

And I have seen many a node taken out that could have been left alone with a few quick exposure questions: any cats? any travel? Been skinning any rabbits in Turlare County? Just how hard is it? Evidently very.

Curious Cases

Relevant links to my Medscape blog

Nodes

Odd Nodes

I don't know what to do.

The Advantage of Screwing Up

Last Update: 11/04/18.