Clinicopathologic diagnosis minimizes misidentification of lymphoma

Boston - Correctly diagnosing the many mimics of lymphoma requires consideration of both clinical and pathological findings, said Antonio Subtil, M.D., M.B.A., at the 2012 American Academy of Dermatology Summer Academy Meeting.

“If the histopathologic findings do not fit the clinical impression, this discrepancy must be addressed and discussed between the dermatologist and the pathologist," says Dr. Subtil, associate professor, departments of dermatology and pathology, Yale University, New Haven, Conn.

Clinical clues
Clinical factors to consider include lesion appearance, including size and distribution, as well as duration, Dr. Subtil says.

"It is also critical not to overinterpret polymerase chain reaction results, since certain benign skin conditions, such as lichen planus or pityriasis lichenoides, may demonstrate T-cell monoclonality,” he explains.

Without any clinical information, "It is often impossible to unequivocally classify individual cases of possible lymphoma on histomorphologic grounds alone,” Dr. Subtil says. “Frequently, the histopathology offers a different diagnosis, and clinical correlation is necessary for a final diagnosis."

Lymphomatoid papulosis (LyP) has several histopathologic types, one of which (type B) is epidermotropic, and histopathologically resembles mycosis fungoides/cutaneous T-cell lymphoma (MF/CTCL), Dr. Subtil says. The distinguishing clinical factor here is that LyP causes small, self-regressing papules, not the large, chronic patches and/or plaques of MF/CTCL.

On the other hand, lymphoma also can mimic benign conditions. "MF/CTCL, the most common type of skin lymphoma, may exhibit a wide variety of histopathologic patterns and may resemble several types of inflammatory dermatoses," such as lichenoid, granulomatous or psoriasiform dermatoses, he says.

Regarding reactions
The lymphoma mimickers that dermatologists see most frequently include drug reactions, Dr. Subtil says.

"Among the clinicopathologic variants of drug eruptions, some cases may be associated with denser cutaneous lymphocytic infiltrates and may resemble both T-cell and B-cell skin lymphomas,” he says. “In addition, several types of infection may be associated with florid, reactive inflammatory infiltrates that may mimic lymphoma."

Conversely, "Some types of pseudolymphomas are uncommon and may cause great diagnostic difficulty,” he says. “For example, leishmaniasis may be associated with a persistent chronic course and a dense lymphohistiocytic infiltrate that may resemble lymphoma."

Somewhat similarly, with the advent of advanced antiretroviral therapy, "Pseudolymphomatous CD8-positive infiltrates in the setting of advanced AIDS have become quite rare,” Dr. Subtil says.

Disclosures: Dr. Subtil reports no relevant financial interests.

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