Fungal infections may mimic malignancies

Quebec City, Quebec - Common diseases can present in unusual ways, so treatment-resistant fungal infections on the skin should be biopsied, as these infections can mimic or coexist with malignancies, according to research presented at the annual meeting of the Canadian Dermatology Association.

Discussing three cases of skin cancers mimicking fungal infections, Afsaneh Alavi, M.D., F.R.C.P.C., a dermatologist at Women’s College Hospital, Toronto and lecturer in the division of dermatology in the faculty of medicine, University of Toronto, stressed the need to avoid diagnosis delays.

“It is important to do a proper skin biopsy,” Dr. Alavi says. “Early diagnosis of these conditions (cancers) can prevent future problems and the need for aggressive treatment of advanced disease. The detection of serious dermatological issues such as malignancies significantly affects patient’s quality of life and the burden on healthcare system.”

In selected cases, clinical criteria alone may not be sufficient to make a diagnosis of a fungal infection.

“A busy practice and cosmetic concerns regarding a scar may be a barrier to (performing) biopsies,” says Dr. Alavi, who stresses that sometimes multiple biopsies are necessary.

“To detect a malignancy in a chronic ulcer, performing multiple and sometimes frequent biopsies from different clinical components of the skin eruption obviate a cancer,” he says. “A negative biopsy for the cancer in a highly suspicious lesion does not rule out the cancer, for there could be a sampling error.

“Close observation of the patient is helpful,” he says. “If it is an ulcer, you need to biopsy from the border and the center of ulcer, to make sure you cover all clinical components of the skin rash. In addition, appropriate biopsy technique avoids diagnostic uncertainties.”

Performing biopsies

Dr. Alavi recommends performing a punch biopsy to increase the accuracy of the diagnosis in most cases. If, however, the changes are in the deep dermis or subcutaneous fat, an incisional biopsy may be preferred. Ultimately, clinicians should have a high degree of suspicion and consider other possible diagnoses when a skin eruption appears as a fungus and does not respond to appropriate therapy, Dr. Alavi explains.

In one case of cancer mimicking fungal infections, a woman with multiple annular skin eruptions over both breasts with discrete borders did not respond to topical antifungal therapy. She had a history of lung cancer that was believed to be in remission. A punch biopsy of the right breast showed cells compatible with metastatic lung carcinoma. The patient was then sent to an oncology center for treatment and was given a prognosis of limited survival, Dr. Alavi says.

There may be other clues that suggest a lesion is not a neurotropic foot ulcer such as the fact that it is not located in a weight-bearing area, explains Dr. Alavi, referring to a case of an elderly diabetic patient who presented with a right foot ulcer in the fourth and fifth interdigital space that was complicated by a secondary bacterial infection and a coexisting fungal infection (tinea ungium).

“The ulcer location was not typical for the neurotropic diabetic foot ulcer and a local ulcer is not a common presentation for a fungal infection,” Dr. Alavi says.

Despite local, topical antifungal treatment and systemic antibiotic treatment for presumed secondary bacterial infection leading to the skin breakdown, the ulcer persisted, notes Dr. Alavi. A skin biopsy was then performed and revealed a squamous cell carcinoma. The patient was treated surgically, and there was full remission.

In the third case, a male patient presented with persistent asymptomatic erythematous patches in the axilla and groin that did not respond to several courses of topical antifungal medicine. A skin biopsy revealed cutaneous T-cell lymphoma, the mycosis fungoides type.

“As the population ages, the rate of cancers primarily involving or invading the skin is increasing overall, so we should be aware of this in our dermatological practices,” Dr. Alavi says.

Dr. Alavi notes several recent reviews in the literature have reported unsuspected malignant cancers presenting in 5 to 15 percent of leg ulcers. The most common malignancy is basal cell carcinoma and the second most common is squamous cell carcinoma, according to Dr. Alavi.¹-²

Disclosures: Dr. Alavi reports no relevant financial interests.