Pyoderma gangrenosum

Abstract

Sir–In his masterly review Jeffrey Callen1Callen J Pyoderma gangrenosum..Lancet. 1998; 351: 581-585Summary Full Text Full Text PDF PubMed Scopus (359) Google Scholar cites some old fashioned haematology. Agnogenic myeloid metaplasia may have been a popular diagnosis in 1976 but it is seldom made today. Most haematologial malignant disease associated with either pyoderma gangrenosum or Sweet's syndrome (which I agree is part of the same spectrum as atypical pyoderma gangrenosum) are related to the myelodysplastic syndrome (MDS). Case reports associating the two2Koester G Tarnower A Levisohn D et al.Bullous pyoderma gangrenosum..J Am Acad Dermatol. 1993; 29: 875-878Summary Full Text PDF PubMed Scopus (52) Google Scholar have become so common as to no longer warrant publication.3Hamblin T Immunological abnormalities in myelodysplastic syndromes..Hematol/Oncol Clin N Am. 1992; 6: 571-586PubMed Google ScholarThis association raises two issues pertaining to diagnosis and pathogenesis. First, MDS is notoriously underdiagnosed, the true prevalence being up to three times greater than is usually reported.4Cartwright RA Alexander FE McKinney PA Ricketts TJ Leukaemia and lymphoma. An atlas of distribution within areas of England and Wales 1984-1988. Leukaemia Research Fund, London1990: 32-40Google Scholar Thus it is quite likely that apparently idiopathic cases have an underlying MDS. Second, MDS is associated with functional abnormalities of granulocytes and macrophages.5Hamblin TJ Immunological abnormalities in myelodysplastic syndromes..Sem Hematol. 1996; 33: 150-162PubMed Google Scholar Immune complexes are the normal consequences of food or bacterial antigens. They are usually disposed of by a properly operating phagocytic system. In MDS, phagocytic dysfunction impairs this process so that immune complexes are deposited in small blood vessels, allowing the local activation of inflammatory mediators. Sir–In his masterly review Jeffrey Callen1Callen J Pyoderma gangrenosum..Lancet. 1998; 351: 581-585Summary Full Text Full Text PDF PubMed Scopus (359) Google Scholar cites some old fashioned haematology. Agnogenic myeloid metaplasia may have been a popular diagnosis in 1976 but it is seldom made today. Most haematologial malignant disease associated with either pyoderma gangrenosum or Sweet's syndrome (which I agree is part of the same spectrum as atypical pyoderma gangrenosum) are related to the myelodysplastic syndrome (MDS). Case reports associating the two2Koester G Tarnower A Levisohn D et al.Bullous pyoderma gangrenosum..J Am Acad Dermatol. 1993; 29: 875-878Summary Full Text PDF PubMed Scopus (52) Google Scholar have become so common as to no longer warrant publication.3Hamblin T Immunological abnormalities in myelodysplastic syndromes..Hematol/Oncol Clin N Am. 1992; 6: 571-586PubMed Google Scholar This association raises two issues pertaining to diagnosis and pathogenesis. First, MDS is notoriously underdiagnosed, the true prevalence being up to three times greater than is usually reported.4Cartwright RA Alexander FE McKinney PA Ricketts TJ Leukaemia and lymphoma. An atlas of distribution within areas of England and Wales 1984-1988. Leukaemia Research Fund, London1990: 32-40Google Scholar Thus it is quite likely that apparently idiopathic cases have an underlying MDS. Second, MDS is associated with functional abnormalities of granulocytes and macrophages.5Hamblin TJ Immunological abnormalities in myelodysplastic syndromes..Sem Hematol. 1996; 33: 150-162PubMed Google Scholar Immune complexes are the normal consequences of food or bacterial antigens. They are usually disposed of by a properly operating phagocytic system. In MDS, phagocytic dysfunction impairs this process so that immune complexes are deposited in small blood vessels, allowing the local activation of inflammatory mediators.