Amir S. Yazdi

The value of molecular analysis by PCR in the diagnosis of cutaneous lymphocytic infiltrates

The diagnosis and classification of cutaneous lymphomas remain a challenge for the clinician and dermatopathologist. This diagnostic dilemma is mainly encountered in the distinction between an early malignant lymphoma and a benign reactive lymphocytic infiltrate (pseudolymphoma). Until the beginning of the 1980s, our diagnostic tools were limited to the clinical presentation, course, and histopathology in diagnosis and classification of lymphocytic infiltrates. Advances in immunology and, in particular, in molecular genetics with the introduction of the Southern blot technique and the polymerase chain reaction (PCR) have revolutionized the diagnosis of lymphocytic infiltrates by determination of clonality. In some series, more than 90% of cutaneous T‐cell lymphomas have a clonal rearrangement of the T‐cell receptor γ‐chain gene, as opposed to very low percentages of rearrangement in T‐cell pseudolymphomas.

Laser-capture microdissection: Applications in routine molecular dermatopathology

Abstract:u2002 Advances in molecular pathology with the introduction of the Southern blot technique and the polymerase chain reaction (PCR) have emerged as important tools, which are frequently used in routine dermatohistopathology. Applications for PCR‐based diagnostics are particularly helpful for the determination of clonality in cutaneous lymphocytic infiltrates and for detection of infectious agents, such as herpes simplex virus (HSV), varicella zoster virus (VZV), Borrelia burgdorferi, Mycobacteria, Leishmania, and Treponema pallidum. As biopsies are always composed of different cells, the cells of interest are often only a minor population. As a consequence, their specific DNA is diluted by the majority of contaminating cells. Another problem is the time‐ and labor‐intensive DNA extraction, because usually only formalin‐fixed, paraffin‐embedded tissue is available, which makes molecular diagnostics a time and labor consuming, and consequently a cost‐intensive procedure. To overcome these shortcomings and to eventually shorten the time to generate a result, we introduce a laser‐capture microdissection (LCM)‐based method for the detection of infectious agents and clonality. Only the cells of interest for the particular indication are microdissected (e.g. epidermal cells for HSV and VZV and lymphocytes for clonality analysis) and subjected to PCR amplification. Due to an accelerated DNA‐extraction procedure which generates DNA in 5u2003h (compared to 3–4u2003days using conventional DNA extraction), we are able to generate a result within one working day.

Improved detection of clonality in cutaneous T‐cell lymphomas using laser capture microdissection

Background:u2002 The diagnosis of cutaneous T‐cell lymphoma is a challenge for both the pathologist and the clinician. This is particularly true for distinguishing early‐stage mycosis fungoides from dermatitis. In this clinical setting, the presence of a clonal T‐cell population supports lymphoma.

Lichen aureus with clonal T cells in a child possibly induced by regular consumption of an energy drink

Lichen aureus is a rare disease of unknown origin that is classified under the group of pigmented purpuric dermatoses. Its most important differential diagnosis is both clinically and histologically mycosis fungoides, into which the disease can proceed in very rare cases. We describe an unusual multilocular lichen aureus possibly induced by the almost daily consumption of an energy drink. An 11‐year‐old boy presented with a history of asymptomatic ochre patches on his extremities and abdomen occurring after regular consumption of an energy drink. Histologic examination showed a band‐like lymphocytic infiltrate, containing hemosiderin deposits and extravasal erythrocytes adjacent to dermal blood vessels, in the iron‐stain detection of hemosiderin. Because of these findings, lichen aureus was diagnosed. After a 2‐month abstention from the energy drink, no new lesions appeared and the present lesions grew pale and finally disappeared. The case shows a rare multilocular lichen aureus, which disappeared after the consumption of an energy drink was stopped. The ingredients of the energy drink are an example of a possible trigger of the disease.