Clinical and histologic features of level 2 cutaneous malignant melanoma associated with metastasis

BACKGROUND

Metastatic melanoma developing in patients with a level 2 primary cutaneous malignant melanoma (CMM) is rare but has been reported in studies with follow-up periods ranging up to 15 years. The objective of this study was to investigate level 2 CMM associated with metastasis in a population-based retrospective study.

METHODS

In this retrospective population-based study, all level 2 CMMs associated with metastases were identified in Western Australia during 1982-1989 and were followed up to the end of 1996.

RESULTS

Pathology reports of 2834 patients were examined. Of these, 1716 had a CMM of maximum tumor thickness 1 mm or less recorded on the pathology report. Of these, 67 had a metastatic melanoma reported on follow-up. Histologic review of these 67 cases under blind conditions identified 5 cases with a level 2 primary CMM followed by metastasis without another primary CMM. All these level 2 CMM showed established regression. Eight other patients were identified with a level 2 CMM, metastatic melanoma, and another primary CMM of at least level 3 invasion. These subsequent primaries occurred before the metastasis had been reported.

CONCLUSIONS

These findings suggest that metastasis from level 2 CMM without regression is very rare, if it occurs at all.

Prognostic significance of MIB-1 proliferative activity in thin melanomas and immunohistochemical analysis of MIB-1 proliferative activity in melanocytic tumors

Metastasis from thin melanomas is rare and unpredictable. In order to assess the prognostic value of the proliferation marker, MIB-1, immunohistochemical staining was evaluated in a retrospective case-control study of 11 thin melanomas with documented metastasis and 11 control tumors that failed to metastasize. Tumors selected were < 1-mm thick and were individually matched for tumor thickness, date of excision, and patient age and sex. Analysis of MIB-1 expression as both a mean and a maximum level for the case and control groups revealed no association with metastasis. Wilcoxon's matched-pairs signed-rank test had p-values of 0.45 for the maximum values and 0.79 for the mean values. For the 11 thin melanomas that metastasized, there was a weak, yet statistically insignificant, correlation between the proportion of cells positive for MIB-1 and the length of the relapse-free period [Spearman's correlation coefficient = 0.20 for the maximum level (p = 0.56) and 0.19 for the mean level (p = 0.58)]. These results suggest that MIB-1 expression may be of limited value as a prognostic marker for increased risk of metastasis in patients with thin melanomas. MIB-1 immunohistochemistry was also performed on 25 benign and 70 malignant paraffin-embedded melanocytic tumors to evaluate the level of MIB-1 expression at different stages of tumor progression. A progressive increase in MIB-1 expression was seen from benign tumors through to primary melanomas, with the highest level seen in metastatic melanomas. Within the group of primary melanomas, the MIB-1 score was shown to correlate significantly with tumor thickness and Clark's level of invasion (Spearman's correlation coefficient = 0.71 for level and 0.77 for thickness).

Contact allergy to chloroacetamide

Chloroacetamide is an uncommon skin care product allergen. A case of allergic contact dermatitis to this preservative is described in a patient who reacted to an underarm deodorant.

Allergic contact dermatitis to 1,2-benzisothiazolin-3-one in the carpet industry

The compound 1,2-benzisothiazolin-3-one (BIT) is the active ingredient in Proxel GXL a commonly used preservative in many industries. The present case report identifies the carpet industry as an additional source of occupational allergic contact dermatitis to BIT.