Risk of malignant transformation of congenital melanocytic nevi in blacks.

The risk of small congenital melanocytic nevi (CMN) developing into melanoma is not known, but is highly controversial. The frequency of small CMN is, paradoxically, slightly higher in some populations, such as blacks, who are at a lower risk of developing melanoma than whites. An estimate of the risk of malignant transformation of CMN in such a low-risk population could help in the management of congenital nevi in these patients and might also shed light on the inherent malignant risk of small CMN. We used a national population-based cancer registry, the Surveillance, Epidemiology, and End Results program (SEER), and the incidence of CMN in blacks taken from published newborn surveys to calculate a risk of malignant transformation. We calculated a maximum risk using a model based on a worst-case scenario, assuming that all melanomas on glabrous skin arise in CMN. We also calculated a modified risk based on the known historical association of nevi and melanomas in blacks, and estimates of the histologic association of the two. The cumulative maximum risk of malignant transformation in blacks to age 75 years was 1 in 164. It was strongly age dependent, with the majority occurring in persons over age 45. The estimated maximum risk before age 15 was less than 1 in 10,000 CMN, and in blacks age 15 to 35 less than 1 in 3700 CMN. The modified risk suggests that the worst-case scenario overestimates the risk by at least a factor of 12, making the actual risk in blacks up to age 75 approximately 1 in 2000.(ABSTRACT TRUNCATED AT 250 WORDS)

Mahogany discoloration of the skin due to the defensive secretion of a millipede.

An 8-year-old boy developed a sudden mahogany discoloration of his skin after exposure to defensive secretions of a millipede. The mechanisms and the composition of the secretion and other clinical features are briefly reviewed.

MR imaging of spindle cell hemangioendothelioma.

Spindle cell hemangioendothelioma is a slowly progressing vascular tumor of low grade malignancy. This neoplasm has been reported in 33 patients but in only one patient were osseous lesions seen. The only other description regarding imaging of this tumor was CT demonstrating soft tissue masses in the thigh without osseous involvement. We present a case of spindle cell hemangioendothelioma in which magnetic resonance further defined the radiographic features of this newly recognized tumor.

The distribution of melanocytic naevi in melanoma patients and control subjects.

A study of 121 melanoma patients and 139 control subjects was conducted among whites to examine and compare the distribution of non-dysplastic and dysplastic naevi and other pigmented lesions in each group. Melanoma patients had a mean of 97 melanocytic naevi which were greater than 2 mm in diameter and controls had a mean of 36 such naevi, while the medians were 58 and 22 respectively (p less than 0.0001). 55% of melanoma patients and 17% of controls had at least one clinically determined dysplastic naevus, and 26% of melanoma patients and 6% of controls had at least 5 dysplastic naevi. Men were found to have more naevi on the trunk than women in both melanoma cases (p = 0.01), and controls (p = 0.005). Dysplastic naevi were most often found on the trunk and were present at this location in 51% of cases and 17% of controls. Melanoma patients and control subjects with dysplastic naevi, when compared to those without these lesions, had larger number of non-dysplastic naevi. Lentigines were more common among melanoma patients that among control subjects (p = 0.02). There were no differences in the number of non-dysplastic naevi among cases with light and dark hair and eyes, or among controls with these characteristics. There also was little variation in the number of naevi according to number of blistering sunburns.

Number of melanocytic nevi as a major risk factor for malignant melanoma.

A study of 121 melanoma patients and 139 control subjects from the University of California, San Francisco clinics was conducted among whites to examine the relationship between number of melanocytic nevi and cutaneous melanoma. Nevi that measured 2 mm or more in diameter were counted over the body by a dermatologist and a dermatology fellow. The average number of nondysplastic melanocytic nevi that were 2 mm or greater in diameter was 97 for melanoma patients and 36 for control subjects (p less than 0.001). Relative risks were 1.6 (p = 0.43) for 11 to 25 nevi, 4.4 (p = 0.01) for 26 to 50 nevi, 5.4 (p = 0.008) for 51 to 100 nevi, and 9.8 (p = 0.001) for more than 100 nondysplastic melanocytic nevi. Relative risks were 3.8 (p = 0.001) for 1 to 5 dysplastic nevi and 6.3 (p = 0.003) for 6 or more of these lesions. Report of blistering sunburns or of a previous skin cancer and having red or blond hair at the age of 20 were also independently associated with an increased risk of cutaneous melanoma. If confirmed in larger studies, the results presented on number of nevi and melanoma risk suggest a readily identifiable melanoma-prone group that could be followed to detect early malignant melanoma.