In this study, a series of aggressively behaving basal cell carcinomas has been contrasted with a series of the nonaggressive type (metastasizing lesions were not considered in this study). Aggressive tumors were characteristically more likely to be ulcerative and infiltrative. They were composed of small groups of cells often displaying an irregular spiky appearance; infiltration of cells in cords, only one or two cells thick, could be seen. There was loss of peripheral palisading: the cells tended not to show differentiation. Hyalinization of the stroma was more common in the aggressive tumors. It is postulated that by utilizing these criteria, the pathologist can confidently diagnose the majority of cases and forewarn the clinician that a particular tumor is potentially aggressive. Adequate treatment and careful follow-up then become feasible.

Objectives To determine the proportion of basal cell carcinomas (BCCs) treated by excision biopsy that extended to the margins of surgical excision (incompletely excised tumours) and to identify their characteristics. Design Case series of BCCs submitted to a single pathologist in the first six months of 1995. Setting Rural and metropolitan (Perth) Western Australia. Patients 268 patients with 353 histologically confirmed BCCs. Outcome measures Age and sex of patients; discipline of referring doctor; anatomical site of BCC; macroscopic features; histological growth pattern; and completeness of excision. Results Sixteen per cent of BCCs (58/353) extended to the margin of surgical excision. Most of these were situated on the head or neck (43/58; 74%) and were flat (47/58; 81%); a high proportion of incompletely excised BCCs (21/58; 36%) had an infiltrative growth pattern. Recurrent BCCs (28/353; 8%), categorised from the history or because of histologically identified surgical scarring, were even more likely to be flat (26/28; 93%) and to show a microscopic infiltrative growth pattern (18/28; 64%). Seven of the 28 (25%) recurrent BCCs were incompletely excised; all seven were on the head and five had an infiltrative growth pattern. Conclusion Incompletely excised BCCs are those most likely to recur. Because most recurrent tumours are situated on the head and neck and have an infiltrative growth pattern, we recommend that: Pathologists report on the microscopic growth pattern of BCCs as well as on completeness of excision. Clinicians attempt to excise head and neck BCCs with wide margins initially, where possible. Tumours extending to the margin of excision which are infiltrative in pattern and located on the head and neck may be particularly likely to recur, and immediate re‐excision should be considered in these patients.

The clinical and histopathological features of a case of solitary extramedullary plasmacytoma of the breast are described. After 46 mth of follow-up, there has been no recurrence of the tumour, and no evidence of further extramedullary plasmacytomas, multiple myeloma or diffuse myelomatosis either clinically, radiologically or on biochemical and haematological investigations. She has developed diabetes mellitus. Distinction is made between the true extramedullary plasmacytoma and those which are a manifestation of multiple myeloma. The unpredictable behaviour and prognosis of extramedullary plasmacytomas is indicated.

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