A number of years ago, a friend was misdiagnosed with cat scratch disease when what she had turned out to be Hodgkin lymphoma. I may be able to use this in a story. Here’s the odd question: What would happen if a person had both illnesses at the same time? I would think the symptoms, which have similarities, would be worse, making the patient seek treatment sooner. Am I correct? Would the diagnosis be more difficult or not?
First, as physicians we are taught a variant of Occam’s Razor – to look for the fewest possible causes that account for all the symptoms. And, ‘when you hear hoofbeats, think horse, not zebra.’ So, if faced with symptoms that could be equally explained by two different diseases, we would generally favor the more common one, and not a combination of the two.
That said, here is a little info on the two diseases:
Cat Scratch Disease
(aka Cat Scratch Fever (but not the album)) is caused by a bacteria and is most common in children. Symptoms begin about 1-2 weeks after a cat scratch or bite, so often the patient has forgotten about the inciting event. Kittens, outdoor cats, and those without flea protection are most likely to harbor the bug. The infection usually resolves on its own in about a month, though rarely can progress to involve the eyes, heart or even brain.
Immunocompromised patients (HIV, certain cancers) are at particular risk for complications including a vascular skin lesion and liver or spleen problems. Diagnosis is challenging. There is a particular stain for use on a lymph node biopsy, but its not perfect. Culturing the bacterium can take several weeks. Another test (PCR) is quicker but only about 50% accurate.
is a white blood cell cancer. About half of cases are caused by a virus (EBV). Most common in 20-40 year olds, patients require chemotherapy, radiation therapy, and sometimes a stem cell transplant. Survival in the US is quite good (>85% at 5 years). The diagnosis is made with a lymph node biopsy showing the cancerous cells.
So if someone had both diseases, their symptoms might be worse, or they might not, depending on how advanced the lymphoma is. At some point they can no longer mount an immune response to the Cat Scratch bacteria and they would miss out on some symptoms. Interestingly, if the patient were in that situation, the Cat Scratch disease could cause liver and spleen problems (cysts), while swelling of those organs is common in Hodgkin’s.
The differential diagnosis (list of possible causative diseases) of enlarged lymph nodes of several weeks’ duration is extensive. Coupled with additional symptoms as noted above, and a concerning medical history, the physician would likely order a biopsy, as well as scans of the body to look for additional abnormalities. Several lab studies would also be checked.
The short answer is, YES, the diagnosis would be more difficult. The biopsy would show Hodgkin’s and that should explain all the symptoms. Unless there was a recent history of a cat scratch or bite, they might not look for it. Whether the cancerous cells could fight the Cat Scratch bacteria is tough to predict, and once they started chemo it could potentially get worse.
I could find no case reports in the literature of a patient with both diseases…but that’s what fiction’s for, right??