exaggerated insect bite like reaction in patients affected by oncohaematological diseases

Sir,Patients affected by chronic B-cell lymphatic leukaemia(CBLL) and, more rarely, other oncohaematologicaldiseases may present with papules, plaques, nodules andvesico-bullous lesions on exposed areas (1–3). Theselesions are usually considered an exaggerated reaction toinsect bites, although the patients not always had ahistory (except for the seasonal presentation of cuta-neous findings), the clinical picture, and response totreatment suggestive of insect bite (3, 4). This phenom-enon has been described in about 40 patients affected bylymphoproliferative disorders, 95% of whom had CBLL(1–7). Weed (1) first gave the definition of 'exaggerateddelayed hypersensitivity to mosquito bites' and reportedthis condition only in patients affected with CBLL.Later, Houston & Keene (2) described a case ofexaggerated insect bite-like reaction also in a patientwith lymphocytic lymphoma. In 1986, Rosen et al. (3)studied 10 patients and suggested that the cutaneouslesions could be linked, in some way, to the onco-haematological conditions, without explaining the exactpathway.Five patients affected by different B lymphoprolifera-tive disorders, who presented with pruritic papules,nodules and vesico-bullous lesions on exposedareas during spring and summer time, are reported.We discuss an immuno-allergic mechanism, involvingboth allergic reaction to insect bite and the impair-ment of the immune response in oncohaematologicalpatients.CASE REPORTSFrom 1995 to 2001, three patients affected by CBLL andtwo by non-Hodgkin B-cell lymphomas attended ourdepartment with polymorphous, erythematous cuta-neous papules and plaques, some of them evolving intobullous lesions. During spring-summer all the patientsdeveloped very itchy lesions, plaques (Fig. 1) andsometimes bullae, mainly localized on upper and/orlower limbs and on the face. Three patients referred tohave been bitten by mosquitoes, the other two deniedthis occurrence. At the time of the clinical examination,all the patients were living in or close to the area ofPavia, Italy, where seasonal infestations of mosquitoes(Aedes) are particularly widespread. All the patientsunderwent a 4-mm punch biopsy, necessary for ahistopathologic evaluation; a direct immunofluores-cence test was carried out for four patients, to excludeautoimmune bullous diseases.At the time of the eruption, one patient was ontreatment with VACOP-B protocol (adriblastina, cyclo-phosphamide, etoposide, vincristine, bleomycin, predni-sone), two patients with chlorambucil and one withcyclophosphamide. An 87-year-old patient was notunder treatment. Blood analysis revealed peripheraleosinophilia in three patients out of five. Stool analysissearching for parasites was carried out in those threepatients and proved negative. IgE was in the normalrange in all the patients. Serum protein electrophoresisrevealed that total immunoglobulins were in the normalrange or little lower in all the patients, while all of thempresented a different degree of decrease of IgG, IgMand/or IgA in sera. The other clinical and serologicalfindings were unremarkable or consistent with theirhaematological condition.The histopathology was characterized by a variety offindings, all of which were consistent with an arthropodbite reaction. In particular, a wedge-shaped, superficialor superficial-deep perivascular and often also inter-stitial infiltrate was present. It was mainly composed ofeosinophils in association with lymphocytes and rarelyneutrophils. The density or the depth of the infiltratevaried from case to case, also according to the age of thelesion. An oedema of the subpapillary dermis wasalways evident. One patient presented a subepidermalvesicle. In another patient spongiosis could be seen an