Sweat gland abnormalities occur much more frequently than hitherto described in cutaneous graft versus host disease (GVHD). Two patterns of abnormalities were identified in 80 per cent of cases of acute GVHD: a cytopathic pattern consisting of a combination of basal vacuolopathy with or without lymphocytic infiltration and basal cell degeneration, and a proliferative pattern consisting of basal cell hyperplasia. In chronic GVHD, complete sweat gland destruction with fibrosis was commonly observed. Squamous metaplasia and dilation of the sweat glands were less frequently identified. Ki67 immunostaining confirmed proliferative activity in the basal cells of the distal duct. HLA-DR antigens were expressed on the basal cells of the duct and secretory glands in acute GVHD but not in normal skin. Langerhans cells were absent in both normal and abnormal sweat glands. The role of HLA-DR or Langerhans cells in the initiation of GVHD is questioned in the light of the new data and the primary involvement of proliferating cells is confirmed.

Graft versus host disease affecting the large bowel causes destruction of the crypt epithelium. There is a selective sparing of enterochromaffin cells in the majority of cases. As a consequence, single as well as small clumps of enterochromaffin cells are to be seen in the sites formerly occupied by the destroyed crypt epithelium. The reason for this phenomenon is unclear, but it may be related to the fact that the enterochromaffin cells are end-stage and non-proliferating cells. This is useful diagnostically. However, cytotoxic drugs or irradiation must be excluded as the cause of the mucosal damage to bowel as there are theoretical reasons to expect that a similar phenomenon will be seen after these forms of therapy.

SUMMARY Ten patients with follicular lymphoma presented with a high white cell count (45-220 x 109/1) which resembled chronic lymphocytic leukaemia (CCL): all had pronounced splenomegaly and, except one, generalised lymphadenopathy. The blood lymphocytes were small with scanty cytoplasm, densely condensed nuclear chromatin, and deep clefts originating in sharp angles from the nuclear surface. CLL cells are larger, have more cytoplasm, a different pattern of chromatin condensation, and may have shallow nuclear indentations or foldings rather than clefts. The circulating follicular lymphoma cells had moderate to strong membrane immunoglobulins (SmIg), low mouse (M)-rosettes, strong reactivity with the monoclonal antibody FMC7, and occasional expression of the CD5-antigen; at least one third of cells in each case were positive with anti-cALLa (J5,CD10). Half the cases were referred as B-CLL but none had the typical B-CLL immunophenotype: weak SmIg, M-rosettes of > 50%, CD5 positive, FMC7 and J5 negative. The diagnosis of follicular lymphoma was confirmed by lymph node biopsy in seven of the 10 cases. The overall response to treatment was poor and five patients died within three years of diagnosis. This aggressive form of follicular lymphoma needs to be distinguished from B-CLL as different management is required.

In mice, i.v. C. parvum induces intravascular coagulation. This is a prolonged reaction lasting up to 7 days. It results in thrombosis in hepatic vessels with consequent hepatic necrosis, and thrombosis in pulmonary and splenic vessels. This may be important in the assessment of the tumour-inhibitory activity of C. parvum. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4

Lichenoid dermatosis is a pattern description of a variety of cutaneous lesions which primarily affect the dermoepidermal junction. Involvement of skin appendages has been restricted to hair follicles in lichen planopilaris and discoid lupus erythematosus. Sweat gland involvement has not been described in the four common members of this group, namely, lichen planus, discoid lupus erythematosus, fixed drug eruptions and erythema multiforme, although structural abnormalities have been reported in graft-versus-host disease. In a detailed morphological study of 59 cases, including lichen planus (12), discoid lupus erythematosus (18), fixed drug eruption (14) and erythema multiforme (15), 78% (47/59) showed sweat, gland abnormalities. The abnormalities included vacuolation of cell cytoplasm, with and without lymphocytic infiltration, apoptosis of basal cells and basal cell hyperplasia of the excretory ducts which predominantly affected the portion of the duct adjoining the acrosyringium. The portion of the duct close to the secretory gland was only involved in continuity and the secretory glands were unaffected. These abnormalities of the sweat gland mostly constitute primary involvement by the disease process in contrast to structural abnormalities secondary to fibrosis.