Pulmonary veno-occlusive disease.

the upper dermis is more intense and some of the deeper dermal vessels are surrounded by inflammatory cells.In a few cases there is more severe vascular damage, which has been interpreted as a vasculitis,5 but R. Marks, M. Black, and E. Wilson Jones3 do not think that vascular damage has a central role in the pathogenesis of the disease.A curious feature in a few acute cases is the presence of unusually large and bizarre mononuclear cells in the infiltrate, which makes it closely resemble a reticulosis, and indeed two cases are known to have progressed to a true lymphona6 8 and ended in death.The name lymphomatoid papulosis has been used for these cases, which were first fully described by V. M. Verallo and J. R. Haserick.Recently Black and Wilson Jones8 have been able to provide details of 15 cases.They are almost certainly variants of pityriasis lichenoides.A few cases have also been reported in association with poikllo.derma (lichenoid parapsoriasis), another potentially prereticulotic condition.9Nevertheless, the great majority of cases of pityriasis lichenoides are entirely benign and the aetiology remains obscure.There is little evidence of any association with other systemic disease, though 11 of 40 patients tested by Marks and colleagues3 showed minor ab- normalities of serum protein.These authors also believe the term parapsoriasis has outlived its usefulness and would be better discarded.Many dermatologists would agree with them.