Steps such as taking a biopsy and obtaining a detailed history will assist in making a diagnosis in challenging and unusual cases. In some instances, such as a case of a patient with strongyloidiasis, it may be necessary to perform multiple biopsies to arrive at a diagnosis.
Melissa Piliang, M.D., F.A.A.D., a dermatologist at the Cleveland Clinic, describes a woman in her late 60s who presented with nodules on her shins that had a pattern of a classic erythema nodosum. She had previously been treated by other physicians for similar episodes that responded to a short course of systemic steroids.
"She had several episodes over several years," Dr. Piliang says. "She would be treated with prednisone, and the nodules would respond quickly."
"The biopsy did not show erythema nodosum, but revealed a medium-vessel vasculitis with a mixed inflammatory infiltrate," she says. "It's a type of vasculitis that is more significant and can be associated with systemic involvement."
The patient was given a course of prednisone and was improving, but the patient had also complained about having shortness of breath when these papules appeared on her lower legs.
"The patient indicated she had a history of asthma," Dr. Piliang says. "Recently, she noted her respiratory symptoms worsened when her legs flared. This additional piece of information was helpful."
Laboratory testing indicated mild peripheral eosinophilia and a positive P-ANCA, confirming the diagnosis of Churg-Strauss Syndrome, a rare hypersensitivity angiitis that can affect internal organs, most commonly the lungs.
The harbinger of the condition was leg lesions, Dr. Piliang says.
The patient is now being followed by a rheumatologist and pulmonary specialist, and is being treated for lung disease. She no longer has leg lesions, Dr. Piliang says.
"The key was to perform a biopsy and ask additional questions about her history," she says.
In another case, a patient who had undergone a pancreatic transplant developed a skin rash, fever and abdominal pain about three months after the transplant.
Transplant clinicians suspected graft versus host disease, Dr. Piliang says.
"We followed the patient for several weeks and performed serial biopsies as the dermatitis evolved," Dr. Piliang says.
"The first two biopsies were non-specific. It was not until a third biopsy that we found the patient had disseminated strongyloidiasis," she says.
Strongyloidiasis is a very rare infection that can be carried asymptomatically in the gastrointestinal tract for years, Dr. Piliang tells Dermatology Times.
This patient suffered from bowel obstructions, likely due to the organism and not her transplant surgery as was initially believed.
Infectious disease specialists treated her for the strongyloidiasis for one week in hospital, and her dermatitis resolved by the time she was discharged. In addition, the organism was cleared from her stool.
"She may have carried this organism asymptomatically in her GI tract for a long time, having acquired it in her childhood," Dr. Piliang says, noting she did a literature search on the disease that described its extended latency.
"It became a problem when she was immunosuppressed after her transplant surgery," she says.
The characteristic cutaneous presentation of disseminated strongyloidiasis is purpura.
"Initially, it was a subtle rash with a little erythema and became more purpuric over the few weeks we followed her, likely due to increasing organism load," she says.
In another case, a patient in her 20s with overall good health presented with blisters on the backs of her hands and forearms that she suspected to be poison ivy. The patient indicated that she developed the rash after gardening.
"She suspected that she had poison ivy," Dr. Piliang says, "but she didn't have the classic itch that is associated with the condition. She described the sensation more as burning or tingling.
"She had diffuse erythema over her dorsal hands, with small papules extending up her forearms, which also doesn't quite fit with poison ivy."
After taking a detailed history, Dr. Piliang found out the patient had made salsa using freshly squeezed limes.
"She made salsa and then went to mow the lawn," Dr. Piliang says. "She had phytophotodermatitis from topical lime juice followed by intense sun exposure."
The patient developed post-inflammatory hyperpigmented macules on the skin where she had the blisters, and Dr. Piliang suggested she use sunscreen to prevent further hyperpigmentation.
"The post-inflammatory hyper-pigmentation confirmed the diagnosis," Dr. Piliang says.
The phenomenon of phytophotodermatitis is not uncommon, but often misdiagnosed by non-dermatologists, she says.