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Anti-mucin variable number tandem repeat (VNTR) antibodies have been used previously to demonstrate the de novo presence of MUC5AC and MUC6 mucin in colorectal adenomas and increased synthesis of MUC2, the major secreted mucin in normal colorectal mucosa. Here we examined secreted mucins in tubular, tubulovillous and villous adenomas of the rectum using non-VNTR antibodies designed to assess mature mucin. Mucin gene messenger RNAs were detected by in situ hybridization. The anti-MUC2 non-VNTR antibody in the goblet cells of adenomas revealed a staining pattern of increased cytoplasmic, Golgi and membrane staining with no change in goblet vesicle reactivity compared with normal controls. In addition, blank goblet cell vesicle immunostaining for MUC2 was found in the transitional mucosa adjacent to all types of adenoma. Although a trend to overexpression of MUC2 was observed with in situ hybridization this was not detected with immunohistology. De novo synthesis of MUC5AC, but not MUC5B or MUC6 mucin was seen in all adenomas and transitional mucosa using immunohistochemistry. There was no correlation of MUC2 or MUC5AC mucin with polyp size or the grade of dysplasia using the non-VNTR antibodies. This study demonstrates that anti-mucin non-VNTR antibodies reveal a different subcellular-localization in rectal adenomas compared with normal colorectal mucosa. Further, this pattern is in contrast to that reported for anti-mucin VNTR antibodies. Combined use of these reagents may benefit future assessment of these cancers.

Purpose Intratumour heterogeneity of uveal melanoma (UM) has become a relevant issue in the era of sampling for prognostication purposes. We present the case of a UM consisting of two very distinct components. Methods A 53‐year‐old man was referred for an infero‐nasal, collar‐stud UM with associated retinal detachment in the right eye. On ultrasonography, the tumour measured 14 x 16mm, with a thickness of 11mm. The patient chose enucleation over other treatment options. The eye was examined morphologically, immunohistochemically and using multiplex ligation‐dependent probe amplification (MLPA). Results Histological sections demonstrated two distinct components: a pale basal part consisting of amelanotic epithelioid melanoma cells with extensive diffuse involvement of the ocular structures. In contrast, the apical part was heavily pigmented comprised only of spindle B cells. Interestingly, MLPA demonstrated complete chromosome 3 loss in the apical (spindle) region but only partial chromosome 3 deletion in the basal (epithelioid) part. Both areas showed polysomy 8. Conversely, immunohistochemistry showed more aggressive features in the basal part rather than in the apical part. Conclusion This case provides further evidence that there is heterogeneity in UM, and that a single intraocular biopsy may not be reliable for prognostication purposes. [ABSTRACT FROM AUTHOR]