Peters, Margot S.

AbstractBackgroundThe term pharmacogenetics is used to describe an evolving field that aims to understand the relationship between individual variations in genetic sequence and differences in the therapeutic and toxic response to medications. The promise of pharmacogenetics is empowerment of clinicians with information that will enable them to personalize drug therapy – to prescribe the right medication at the right dose for each patient, while minimizing adverse effects. Despite dramatic advances, wide application of pharmacogenetics to clinical practice has been slow for a number of reasons, including lack of evidence‐based therapeutic guidelines as well as ethical concerns and cost.MethodsTo illustrate applications to dermatology practice, we present three clinical scenarios that serve as a springboard for discussion of the principles of pharmacogenetics and how they can be used to guide treatment with azathioprine, 5‐fluorouracil, and trastuzumab.ConclusionThe therapeutic and toxic effects of a given medication ultimately depend on its combined pharmacokinetic, pharmacodynamic, and pharmacogenetic properties in a given individual. Pharmacodynamic properties of individual medications must be correlated with single nucleotide polymorphisms. Test recommendations and standardization of therapy for specific disorders can then be established.

Generalized eruptive histiocytosis, described in 1963 by Winklemann and Muller, is a reactive, self‐healing form of non‐Langerhans histiocytosis. Rare cases of atypical generalized eruptive histiocytosis have been reported in patients with hematopoietic malignancy, but the biological relationship between the two disorders is not known. We report an 84‐year‐old man with chronic myelomonocytic leukemia who presented with coalescing erythematous papules and plaques on the posterior neck, ear and lower lip, followed by development of blast crisis. Skin biopsy revealed a thick band‐like dermal infiltrate of cells that exhibited morphologic features of macrophages or histiocytes and prominent elastolytic phagocytosis. These cells demonstrated a mature immunophenotype, expressing CD14 and CD68, with partial expression of CD13 but not CD1a, CD43, CD56, CD123, Langerin, or S‐100 protein. Karyotype and fluorescence in situ hybridization analyses showed loss of the Y chromosome in bone marrow and skin specimens, providing evidence of a clonal relationship between the cutaneous eruption and the underlying chronic myelomonocytic leukemia. The presence of the same clone in skin and bone marrow specimens from our patient supports the possibility that atypical generalized eruptive histiocytosis is a marker for underlying hematopoietic malignancy. Discovery of additional cases may shed further light on the pathogenesis of this rare entity.

AbstractIntercellular adhesion proteins are poorly characterized in acantholytic squamous cell carcinoma (ASCC), a more aggressive tumor than nonacantholytic invasive well-differentiated squamous cell carcinoma (SCC) of the skin. In this study we compared expression of Dsg3, E-cadherin, and syndecan-1 in ASCC and SCC. Immunohistochemical detection of Dsg3, E-cadherin, and syndecan-1 in 22 ASCCs and 22 SCCs was graded on a semiquantitative scale for intensity of staining (SI) and degree of circumferential staining (CS) about the cell membrane. Results were assessed by means of conditional logistic regression and χ2 analysis. Dsg3 and E-cadherin expression (SI, CS) was significantly decreased (P < .05) in ASCC compared with SCC, whereas staining for syndecan-1 was similar in the 2 tumor types. Differences in expression of adhesion markers between ASCC and SCC may contribute to the development of acantholysis in ASCC and its more aggressive biologic behavior.

AbstractSchnitzler's syndrome is characterized by recurrent urticarial rash and monoclonal gammopathy, associated with clinical and biological signs of inflammation and a long‐term risk of AA amyloidosis and overt lymphoproliferation. An extensive literature review was performed, and the following questions were addressed during an expert meeting: In whom should Schnitzler's syndrome be suspected? How should the diagnosis of Schnitzler's syndrome be established? How should a patient with Schnitzler's syndrome be treated? How should a patient with Schnitzler's syndrome be followed up?. A diagnosis of Schnitzler's syndrome is considered definite in any patient with two obligate criteria: a recurrent urticarial rash and a monoclonal IgM gammopathy, and two of the following minor criteria: recurrent fever, objective signs of abnormal bone remodeling, elevated CRP level or leukocytosis, and a neutrophilic infiltrate on skin biopsy. It is considered probable, if only 1 minor criterion is present. In patients with monoclonal IgG gammopathies, diagnosis is definite if three minor criteria are present and possible if two are present. First‐line treatment in patients with significant alteration of quality of life or persistent elevation of markers of inflammation should be anakinra. Follow‐up should include clinical evaluation, CBC and CRP every 3 months and MGUS as usually recommended.

Cutaneous gamma‐delta T‐cell lymphoma (γδTCL) is a rare malignancy that typically displays an aggressive clinical course. We present an unusual case of a 57‐year‐old woman with a 3‐year history of lower extremity nodules. Histopathologic, immunophenotypic and molecular genetic studies revealed a clonal, predominantly pannicular gamma‐delta T‐cell infiltrate, leading to a diagnosis of cutaneous γδTCL. The clinical course was characterized by rapid improvement within months of starting systemic corticosteroids, with relapse in ulcerations but no new lesions more than 3 years after onset of disease. Our case and seven previously reported patients with indolent and relatively localized cutaneous γδTCL provide evidence that not all cases of this entity carry a poor prognosis. This indolent subset adds complexity to treatment of cutaneous γδTCL.

BackgroundCutaneous granulomatous inflammation can occur in patients with T‐cell lymphoma and Hodgkin disease. We describe the unusual microscopic pattern of a granuloma annulare (GA)‐like eruption co‐existing with B‐cell chronic lymphocytic leukemia (B‐CLL).MethodsWe reviewed the histopathology and immunophenotype of skin biopsies from two patients with B‐CLL and cutaneous lesions resembling GA.ResultsBoth patients had symptomatic cutaneous lesions clinically resembling GA; one had lesions refractory to standard dermatologic therapy. Histopathology showed GA‐like palisaded histiocytic infiltration, with subtle collections of lymphocytes interspersed among the granulomatous inflammation. Immunohistochemistry showed strong expression of CD20 and CD79a, with aberrant CD5 co‐expression, confirming cutaneous involvement by B‐CLL.ConclusionsCo‐existence of a GA‐like infiltrate and cutaneous B‐CLL raises the possibility that granulomatous inflammation occurs as a secondary response to dermal infiltration by leukemic cells. Because histopathologic findings can be subtle, knowledge of this association is essential to avoid overlooking the diagnosis. Regardless of whether histopathology reflects a reactive or primary phenomenon, documentation of cutaneous involvement by B‐CLL may serve as a rationale for specific treatment of the underlying B‐CLL in patients with skin lesions unresponsive to dermatologic therapy and for whom there is no other justification for leukemia‐targeted therapy.