[Histiocytic cytophagic panniculitis]

A HISTOPATHOLOGICAL DIAGNOSIS: Histiocytic cytophagic panniculitis is the specific skin finding in the reactive hemophagocytic syndrome. It is a feverish nodular eruption which accompanies the other clinical and biological features of the reactive hemophagocytic syndrome. Histopathologic changes are diagnostic and consist in a lobular panniculitis characterized by the presence of a histiocytic infiltration of the fat. Histiocytes are benign in appearance and show variable degree of phagocytosis.

INFECTION AND IMMUNE ANOMALIES

In more than 50% of the cases, the disease is triggered by an infection (mainly a viral infection from the herpes-virus family) in a patient with altered immune function (immunodeficiency, autoimmune disease, hematological disease). Search for subcutaneous T-cell lymphoma is mandatory, but is a diagnostic challenge. Such lymphomas are associated with histologic features of histiocytic cytophagic panniculitis.

PATHOPHYSIOLOGY

Histiocytes in the histiocytic cytophagic panniculitis are activated by an abnormal cytokine secretion (interferon gamma, granulocyte/macrophage colony stimulating factor, phagocytosis inducing factor, ...) from neoplastic or reactive T cells.

CLINICAL TRIALS

Untreated, the course of the disease is usually lethal. Etiologic treatment should be provided whenever possible. Symptomatic treatment consists in transfusion and corticosteroid therapy. Etoposide, and sometimes cyclosporin, have been reported to be efficient. Some authors recommend that histiocytic cytophagic panniculitis should always be treated with a CHOP-like polychemotherapy. More recently, good results were obtained with high dose intravenous immunoglobulin and this treatment therefore deserves further evaluation.

Genital ulceration revealing a primary cutaneous anaplastic lymphoma

Images

Examination of cutaneous macroglobulinosis by immunoelectron microscopy

Cutaneous macroglobulinosis is a rare cutaneous manifestation of Waldenström's disease. Lesions are though to result from accumulation of macroglobulin in the dermis and are therefore called IgM storage papules. Ultrastructural findings in the previously reported cases were contradictory and the nature of the deposits was not established by electron microscopy. The purpose of this study was to analyse such deposits by the use of immunoelectron microscopy. A 60-year-old woman had multiple erythematous papules for 1 year. The histopathological changes consisted of plasmocytic infiltration of the dermis and eosinophilic deposits. The skin changes and other investigations led to a diagnosis of Waldenström's disease. Samples from normal and diseased skin were analysed by electron microscopy and by immunogold labelling with anti-IgM antibodies, after Lowicryl K4M embedding. An extracellular electron dense granular and filamentous material was observed in the mid- and upper dermis, between and within the collagen bundles. No periodicity was noted and no deposits were seen at the dermoepidermal junction. Immunoelectron microscopy showed a positive labelling located only on these deposits, in both normal-appearing skin and in lesions. In this patient, immunoelectron microscopy clearly demonstrated the presence of large amounts of IgM in the dermis, which were found in the lesions of cutaneous macroglobulinosis and in normal skin. These results suggest that the IgM storage papules result from a greater density of deposits rather than a site-specific accumulation.