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PubMed1990

Evaluation of DNA ploidy in dysplastic and Spitz nevi by flow cytometry.

As many as 40% of all primary cutaneous melanomas can have histologic remnants of nevomelanocytic nevi adjacent to the tumor. There is increasing evidence that dysplastic nevi are at least a clinical marker for melanoma risk. Spitz nevi are not known for such an association, but are noteworthy because of their histologic appearances. Spitz and dysplastic nevi were studied by flow cytometry to search for DNA abnormality. The study material consisted of formalin-fixed, paraffin embedded material of 41 dysplastic nevi and 14 Spitz nevi. Four cases of dysplastic nevi were excluded for technical reasons. Of the 37 interpretable histograms from dysplastic nevi, 28 (76%) were diploid and nine (24%) were aneuploid. All the Spitz nevi were diploid. Thus, dysplastic nevi, but not Spitz nevi, share aneuploidy features in some cases with melanoma. Previous authors have demonstrated aneuploidy in melanoma with aggressive behavior and in those in deep vertical growth phase. Aneuploidy may be a feature of early as well as late stages of tumor progression regarding the nevomelanocyte system.

DNA, Neoplasm↗
PubMed1999

Dysplastic changes in different types of melanocytic nevi. A unifying concept.

We observed histopathologic changes previously described in dysplastic melanocytic nevi in association with a dermal component characteristic of other types of melanocytic nevi or overlapping with features of other varieties of nevi. In order to determine the frequency of these changes, we studied 2,164 cases of compound melanocytic nevi that fulfilled the histopathologic criteria for the diagnosis of compound dysplastic nevus, including architectural pattern, cytologic features, and mesenchymal changes. Of the 2,164 compound dysplastic melanocytic nevi, 1,895 (87.6%) had the histopathologic characteristics previously described for dysplastic nevus, 179 (8.3%) showed a dermal component with a congenital pattern, 67 (3.1%) demonstrated epidermal and dermal characteristics of Spitz's nevus, 8 (0.3%) had features of a combined blue nevus, 13 (0.6%) had a halo phenomenon and 2 (0.1%) showed dermal neuronevus. By considering these nevi as variants of dysplastic nevi, one may apply a unified conceptual basis for their nomenclature. In order to completely describe the appearance of the nevus, we named them by adding the term "dysplastic", to their main histopathologic subtype. Accordingly, six different varieties of dysplastic nevi were identified: 1) dysplastic nevus (original); 2) dysplastic nevus with a congenital pattern; 3) dysplastic Spitz's nevus; 4) dysplastic combined blue nevus; 5) dysplastic halo nevus; and 6) dysplastic neuronevus. In summary, we conclude that the histopathologic criteria previously reported for the diagnosis of dysplastic nevi may be found in association with a dermal component characteristic of other types of melanocytic nevi or may have overlapping features with other variants of nevi.

Adolescent↗
PubMedDate not supplied

Influence of PUVA therapy on dermoscopic features of acquired melanocytic nevi.

The aim of the present study was to investigate whether PUVA therapy can induce changes in the dermoscopic image of acquired melanocytic nevi. In this study, 28 acquired melanocytic nevi of 14 patients undergoing PUVA therapy were examined. Two nevi of morphologically similar features were selected in each patient. During UVA radiation, 14 nevi were protected from UVA exposure and 14 nevi were left unprotected. Before and after 3 months of PUVA therapy, all nevi were documented under standardized conditions by means of a Dermaphot apparatus. Color dermoscopic images of all nevi were examined by two investigators for size, color and structural features (pigment network-streaks, brown globules, black dots). After PUVA therapy, an increase in size (p < 0.05 in protected nevi and p < 0.01 in unprotected nevi) and a general color darkening (p < 0.01 for both groups) were documented in both groups. While significant structural changes (broadness of pigment network, formation of focal branched streaks, increasing in number and size of brown globules) were detected in unprotected nevi (p < 0.05), no significant changes were in protected nevi (p > 0.05).

Adolescent↗
PubMed1995

The risk of melanoma in patients with congenital nevi: a cohort study.

BACKGROUND: Giant congenital nevi are associated with a greatly increased risk of melanoma, but this has not been quantified. Smaller congenital nevi are believed by some authors to be associated with increased risk, but this is uncertain and needs to be clarified. OBJECTIVE: Our purpose was to analyze cause-specific mortality and cancer incidence risks in patients with congenital nevi according to size of the nevi. METHODS: We followed up 265 patients with congenital nevi first treated at the Hospital for Sick Children or at St. John's Hospital in London during 1950 to 1984 for mortality to mid-1993 and for cancer incidence from 1971 to 1989. Mortality and cancer incidence rates in the cohort were compared with expectations from national mortality and cancer incidence rates by sex, age, and calendar period. RESULTS: Among the 33 patients with a congenital nevus covering at least 5% of the body area, two melanomas occurred during follow-up; both were fatal. The relative risk of melanoma mortality in these patients was 1046 (95% confidence interval, 127 to 3779). In the remaining 232 patients, 68 of whom had a nevus covering 1% to 4% of the body, and 164 with nevi smaller than 1% of body area, no melanomas occurred (0.18 melanoma deaths expected). The difference in melanoma mortality risk between the group with a nevus covering at least 5% of the body and the group with smaller nevi was significant (p < 0.05). There was not a significantly increased risk of nonmelanoma mortality or of nonmelanoma cancer incidence overall in the cohort, although two lymphohematopoietic malignancies occurred. CONCLUSION: The data show the large risk of melanoma in patients with nevi covering more than 5% of the body surface area. The results do not support the hypothesis of greatly increased risk in persons with congenital nevi smaller than this, but because the confidence intervals of the result were wide, the data are compatible with a sizable risk. Much larger studies than those that have so far been undertaken, or combined analysis of data from several studies, are needed to quantify more precisely the risk of melanoma in relation to size of nevi and to determine the appropriate clinical management of these lesions.

Adolescent↗
PubMed2005

Anatomical and histopathological correlates of the dermoscopic patterns seen in melanocytic nevi on the sole: a retrospective study.

BACKGROUND: Anatomical and histopathologic correlates of the unique dermoscopic patterns seen in melanocytic nevi on acral volar skin is yet to be clarified. OBJECTIVE: Our aim was to investigate the relation between the dermoscopic patterns and anatomical and histopathological characteristics of melanocytic nevi on the sole. METHODS: The precise locations of 298 melanocytic nevi on the sole from 278 patients were retrospectively investigated, with attention paid to each dermoscopic pattern. In addition, 35 nevi showing each typical dermoscopic pattern were excised and evaluated histopathologically. RESULTS: Melanocytic nevi showing the parallel furrow pattern or the fibrillar pattern were located on the portions of the sole with regular parallel skin markings and were not found on the arch areas of the foot. Moreover, a subtle but distinctive difference in the distribution was observed between nevi of the two patterns; the nevi with the fibrillar pattern showed a tendency for the sites directly pressed by the body's weight. Melanocytic nevi of the lattice-like pattern were mostly located on the arch areas. Histopathologically, irrespective of the dermoscopic patterns, nests of nevus cells were mainly located in the epidermal rete ridges underlying the surface sulci. In the nevi with a fibrillar pattern, the cornified layer showed a slanting arrangement, which is considered to be a histopathological background of the fibrillar pattern. CONCLUSION: Dermoscopic patterns seen in acral melanocytic nevi could be explained by the unique anatomical and histopathological characteristics of the acral skin.

Adolescent↗
PubMed1998

Atypical melanocytic nevi of the genital type with a discussion of reciprocal parenchymal-stromal interactions in the biology of neoplasia.

UNLABELLED: Melanocytic lesions of the genital area, especially those on the vulva, may present great difficulty in histological interpretation. A histological diagnosis of malignant melanoma was made in more than one third of 56 genital area melanocytic lesions submitted in consultation to the authors. The median age of the patients with these lesions was 25 years. This article is a clinicopathological study of these lesions and distinguishes them from malignant melanoma. The stroma of the lesions of the genital area was different from the stroma seen in the dysplastic nevi and melanoma. The differences in the stromal form in the diverse lesions is useful in diagnosis and is of profound biological significance. The stroma in the reported lesions and in some lesions of melanocytic neoplasia is described in detail, and its biological significance is discussed. Three sets of cases are used in this comparative study to delineate the clinicopathological nature and the biology of the genital nevi. The 56 cases submitted in consultation constitute the primary series of our work (The Clark Cutaneous Pathology Laboratory Series). These are compared with a series of cases from the Pigmented Lesion Group of the University of Pennsylvania and Pathology Services, Inc, and another series of cases from the Genetic Epidemiology Branch of the National Cancer Institute. The two series used for comparative study contain approximately the same number of cases of dysplastic nevi and malignant melanoma as there are atypical melanocytic nevi of the genital type in the primary series. The total number of cases was studied by comparison of their attributes in a relational database. The clinical data of the primary series was acquired through the use of a questionnaire completed by the contributors. The 56 cases presented two distinctive pathological pictures. One of these is termed atypical melanocytic nevi of the genital type (AMNGT), whereas dysplastic nevi (DN) formed the second of the two pathological pictures. There were 36 AMNGT and 14 DN. The remaining six cases were common nevi without atypia or ill-defined melanocytic hyperplasias. The lesions of AMNGT are usually located on the vulva, but they are seen on the perineum and, rarely, on the mons pubis and in the axilla. Lesions similar to AMNGT have been seen uncommonly on the male genitalia. The stromal patterns were distinctive and related to specific melanocytic lesions. An unclassified (unclass) or nonspecific stromal pattern was associated with AMNGT; a pattern of regression with differentiation (diff-regress) dominated the stroma of common dermal nevi; concentric eosinophilic fibroplasia (cef) and lamellar fibroplasia (lf) were present in dysplastic nevi; fibroplasia with a plaquelike lymphocytic infiltrate (fl) and diffuse eosinophilic fibroplasia (def) were noted in radial growth phase melanoma; and fibroplasia with angiogenesis (fa) or an absence of evidence for parenchymal stromal reciprocal interactions (nopsi) marked thick or deeply invasive vertical growth phase melanomas. Recommendations for management of the lesions are suggested. CONCLUSIONS: One kind of atypical melanocytic proliferation in the genital area forms a distinctive clinicopathological entity that can be distinguished from melanoma and dysplastic nevi, the AMNGT. Such lesions are more common on the labia minora or the mucosa of the clitoral region than they are on the labia majora. The other common atypical melanocytic proliferation of this area is a dysplastic nevus, which is much more common on the labia majora than on the labia minora. The reciprocal interactions between parenchyma and stroma are discussed as homeostatic processes, a continually functioning template maintaining tissue, organ, and organismal form and function. The progressive disorganization of this template in neoplasia is illustrated and is considered to be a cardinal element in the biology of neoplasia.

Adolescent↗
PubMed1997

Influence of UVB therapy on dermoscopic features of acquired melanocytic nevi.

BACKGROUND: Exposure to UV radiation can lead to clinical, histologic, and ultrastructural changes in acquired melanocytic nevi. OBJECTIVE: We investigated whether UVB therapy can induce changes in melanocytic nevi detectable by dermoscopy. METHODS: Eighty acquired melanocytic nevi of 13 patients (10 females, 3 males; mean age, 28 years; range, 13 to 62 years) undergoing UVB therapy were documented under standardized conditions by means of a Dermaphot apparatus before and at the end of suberythemal UVB therapy. The mean duration of therapy was 8 weeks (range, 2 to 17 weeks) and the mean total UVB dose was 1120 mJ/cm2 (range, 247 to 2771 mJ/cm2). During UV irradiation, 40 nevi were left unprotected and 40 nevi were protected from UV exposure in a randomized manner. Color dermoscopic images of nevi before and after UVB therapy were projected side by side and examined blindly by five investigators. Fifteen different features were evaluated in the nevi. RESULTS: Unprotected nevi became more irregular (p < or = 0.01) and darker brown (p < or = 0.03) by the end of the therapy, whereas the protected nevi showed no significant changes. CONCLUSION: Suberythemal UVB therapy can lead to changes in the dermoscopic image of acquired melanocytic nevi, presumably by activating melanocytes.

Adolescent↗
PubMed1991

Inter-clinician agreement on the recognition of clinical pigmentary characteristics of patients with cutaneous malignant melanoma. Studies of melanocytic nevi, VI.

The number and type of melanocytic nevi are among the most important known predictors of risk for cutaneous malignant melanoma. In this study, examinations of the skin were conducted by two to four clinicians on 153 patients with newly diagnosed melanoma, and the agreement among clinicians was quantified regarding number of nevi and freckling. The index of agreement (calculated as the intra-class correlation coefficient) was 59.7% and 69.0% for freckling on the right forearm and on the shoulders, respectively; agreement was above 50% for only one of six pairs of clinicians in examining freckling on the right forearm, while agreement was above 50% for four of the six pairs of clinicians in examination of freckling on the shoulder. For palpable nevi of the arms (used in at least two case-control studies as a predictor of risk), the agreement was 36.1% when computed for three examiners assessing 81 patients. However, for total arm nevi (both palpable and non-palpable), assessed on a subset of 48 patients, the agreement was 88.2%; this and other analyses indicated that the difficulty in achieving a consensus for palpable nevi lay in whether or not lesions were considered to be 'palpable' or 'non-palpable'. Agreement for total number of atypical nevi on the body and total number of all types of nevi were 87.4% and 91.8% respectively. These data suggest that the kinds of lesions on which agreement might be reached are total atypical nevi and total nevi of all types on the arms and on the entire body. Greater difficulty might be found in achieving consistency among investigators and among clinicians in examining individual patients with respect to freckling on the arms and 'palpable' nevi. However, some consistency was achieved even with these latter two clinical features.

Adult↗
PubMedDate not supplied

Congenital nevocytic nevi: follow-up of a Swedish birth register sample regarding etiologic factors, discomfort, and removal rate.

Congenital nevi both small and large are frequently removed. We attempted to study the removal rate and etiologic aspects of congenital nevi as well as their psychosocial effects through the use of a quality test. A questionnaire sent to a sample population of individuals with congenital nevocytic nevi (n=192) collected from the Swedish Medical Birth Register (SMBR) was used as a test of the register's quality and for collecting information on rate of removal and etiologic factors. The quality test indicated that only 85.3% of the nevi listed in the SMBR were true congenital nevocytic nevi. Of all true congenital nevocytic nevi reported in the questionnaire, 39.8% had been removed and none of the rest had developed malignant melanoma. The median time for follow-up was 14 years. The median age at removal of the nevi was 9.7 years. Eight percent of respondents believed that the skin lesion caused taunting and changed their social activities. No infection or illness during pregnancy was specifically related to the development of congenital nevi. In conclusion, the larger the nevi, the more frequently and earlier they are excised. With an excision rate of 40% of congenital nevocytic nevi, we found no malignant melanoma.

Adolescent↗
PubMed2001

Pointillist nevi.

BACKGROUND: Atypical melanocytic nevi and cutaneous melanoma are often marked by variation in color. However, there are examples of "benign" explanations for irregularities in pigmentation, such as perifollicular hypopigmentation or hyperpigmentation. OBJECTIVE: The purpose of this study was to correlate the clinical and histologic features of 3 unusual melanocytic nevi consisting exclusively of multiple, tiny, dark brown to black dots on a skin-colored background, which we have termed pointillist nevi. METHODS: Histologic examination was performed of the single pointillist nevus from each of 3 patients (all women; aged 28, 39, and 47 years). RESULTS: The diameters of the pointillist nevi were 2, 3.5, and 5.5 mm. Individual dots were approximately 0.1-0.25 mm. Each of the 3 nevi showed a different histologic correlate for the dots, either (1) discrete, densely pigmented, junctional melanocytic nests; (2) isolated dermal pigmented melanocytic nests; or (3) discrete clusters of melanophages in the papillary dermis. CONCLUSION: Pointillist nevi are benign melanocytic nevi with histologic correlates similar to those of the "brown globules" observed by dermoscopy in uniformly pigmented nevi. However, the dots seen in pointillist nevi can be visualized without magnification. The clinical and histologic features of pointillist nevi add to the spectrum of unusual patterns of pigmentation that may be encountered in benign melanocytic lesions.

Adult↗
PubMed1999

Persistent and recurrent blue nevi.

Persistence of common melanocytic nevi has been fairly well characterized, clinically and histologically. In contrast, persistence of blue nevi has been reported infrequently. To define this entity better, nine cases of biologically persistent and clinically recurrent blue nevi are described. The persistent lesions in four cases were spindle-fascicular blue nevi; one showed senescent or "ancient" change and one had additional deep penetrating/epithelioid blue nevus features with atypical changes worrisome for malignancy. These changes included increased cellularity, cellular pleomorphism, mitotic figures, and a lymphocytic infiltrate. Three were biphasic dendritic-sclerotic/spindle-fascicular blue nevi, one of which had atypical changes. One case was a dendritic-sclerotic ("common") blue nevus. The original histology in one case was unavailable, but the recurrence was a combined blue nevus. The interval from initial biopsy to biopsy of the recurrent lesion was often longer (mean 2.7 years) for recurrent blue nevi than for recurrent common compound or intradermal melanocytic nevi. In addition, in contrast to recurrent common melanocytic nevi, the recurrence, in at least one case, extended beyond the scar of the original excision. These cases demonstrated that blue nevi of all histiotypes and combinations are capable of persistence with clinical recurrence. The persistence usually was histologically similar to the original, but in some cases was more "cellular" because, for the most part, the excisions of the persistent lesion revealed a deeper spindle-fascicular ("cellular") component not evident in the original superficial biopsy. In two cases, the original blue nevus appeared completely banal, but the persistent/recurrent lesions were histologically distinct and demonstrated atypical histologic features. Yet, follow-up (average 3.7 years) supports benign biology. Clinical recurrence is often associated with malignant transformation in blue nevus, but this series demonstrates that malignant tumor progression is not necessarily the case. In the absence of necrosis en mass, marked cytologic atypia, and frequent mitotic figures, the described atypical morphologic parameters in previously biopsied small blue nevi are probably reactive and "pseudomalignant." Awareness of this potential change may avoid diagnostic and prognostic errors.

Adolescent↗
PubMed2000

Immunohistochemical distinction of epithelioid histiocytic proliferations from epithelioid melanocytic nevi.

Histiocytic tumors can be confused with melanocytic nevi and malignant melanoma and vice versa. To explore the use of immunohistochemistry for this diagnostic problem, we examined the expression of S-100 protein, gp100 (the antigen recognized by HMB-45), tyrosinase (T311), Melan-A (A103), Factor XIIIa (FXIIIa), and CD68 in 10 juvenile xanthogranulomas (JXGs), five epithelioid histiocytomas (EHs), and 15 melanocytic nevi composed of large epithelioid cells. All epithelioid melanocytic nevi were immunoreactive for Melan-A, tyrosinase, and S-100 protein in most melanocytes. Four nevi were completely negative with HMB-45. Nine nevi had only a minor HMB-45-positive component in the superficial dermis. Two nevi were diffusely HMB-45-positive. Melanocytes in all nevi were completely negative for FXIIIa. Thirteen nevi were completely negative for CD68. Two nevi contained rare cells with weak staining for CD68. All 15 histiocytic proliferations were completely negative for Melan-A, tyrosinase, and gp100. They lacked expression of S-100 protein or had at most 10% immunopositive cells. In JXGs, most cells were strongly reactive for CD68, although only a few were positive for FXIIIa. In EHs, 40% to 60% of cells were immunoreactive for FXIIIa, and only 20% to 30% were positive for CD68. Our results demonstrate that Melan-A and tyrosinase are sensitive and specific markers to distinguish epithelioid melanocytic nevi from epithelioid histiocytic tumors.

Antigens, CD↗
PubMed2000

Small congenital nevi associated with melanoma: case reports and considerations.

Melanocytic nevi, both congenital and acquired, are considered to be precursors of melanomas. Data about the malignant potential of these nevi are conflicting, particularly with reference to the nevus of the smallest size. Patients with preexisting melanocytic nevi (both congenital and acquired) have risks of developing melanoma that differ from those of subjects without them. The purpose of this study was to verify the presence of melanoma in preexisting nevi both congenital (congenital nevus associated melanoma) (CNAM) and acquired (ANAM). In particular, we investigated melanomas associated with small congenital nevi (SCN). A cohort of 190 patients with primary melanomas was studied. Congenital nevi were called "small" (SCN) when their diameters were less than 1.5 cm. Epiluminescence microscopy (ELM) was performed to further improve the clinical diagnosis and to observe the more subtle changes in the preexisting nevi. Forty of the 190 cases of melanoma were associated with preexisting nevi; of these, 15 had congenital features with a CNAM largest diameter of 1.5 cm. These 15 cases were melanomas of the superficial type with a mean tumor thickness lower than that of ANAM (0.33 vs 1.50). There were no differences between the locations of CNAM and other melanomas. Male patients were significantly more affected. ELM microscopy permitted us to detect the early malignant changes in nevi and thus to improve our diagnosis. A high percentage of small congenital nevi were found to be associated with melanomas. They may be considered as melanomas precursors. Because of their large number and frequency, prophylactic removal of all SCN is not feasible. However, they should be removed as soon as possible when clinical or ELM changes are observed.

Adult↗
PubMed1992

Prevalence of dysplastic nevi in healthy young men.

Young white men (1176 men, mean age 20 years, age range from 18 to 26 years) were examined for dysplastic nevi. In 78 patients (6.63%), 107 clinically dysplastic nevi were observed, demonstrating all three NIH criteria (diameter greater than 5mm, irregularities of border, irregularities of color) suggestive for clinically dysplastic nevi. Of these, 71 nevi in 52 patients were excised and examined histologically, 46 nevi in 26 patients were not excised due to lack of patients' consent. Fifty-two of 78 (66.6%) patients with clinically dysplastic nevi agreed to excision. In these, seven nevi (13.5% of patients or 9.86% of all nevi excised) were confirmed by histology. According to these data, three additional patients with dysplastic nevi would have been expected among the 26 patients who refused surgery. Referring to the entire study group, the prevalence of dysplastic nevi in young white men is expected to be 0.85%.

Adolescent↗
PubMed2006

Efficacy and safety of the short-pulse erbium:YAG laser in the treatment of acquired melanocytic nevi.

BACKGROUND: Various laser systems have been used in the treatment of acquired melanocytic nevi. However, CO2 lasers may cause scarring, and some nevi cannot be removed with pigment-specific lasers completely. To date, no study has evaluated the efficacy and safety of an erbium:yttrium-aluminum-garnet (YAG) laser, with its small penetration depth and fewer adverse effects, in the treatment of acquired melanocytic nevi. OBJECTIVE: To investigate the efficacy and safety of the short-pulse erbium:YAG laser in the treatment of acquired melanocytic nevi. METHODS: The study included 28 nevi in 14 patients. The lesions were pigmented, flat, or just palpable nevi. Nevi were irradiated with single-pulse laser energy of 1,000 mJ and a pulse duration of 300 microseconds. Fluences between 5.2 and 14.4 J/cm2 were used. Four months following laser treatment, the entire lesion was excised. Each specimen was histopathologically and immunohistochemically examined for the presence of nevus cells. RESULTS: Clinically, all of the nevi and, histopathologically, 27 of 28 nevi (96%) were completely removed without scarring. Post-inflammatory hyperpigmentation was seen in two patients and hypopigmentation in three patients. CONCLUSIONS: Short-pulse erbium:YAG laser treatment is an effective and safe method for removing acquired melanocytic nevi.

Adult↗
PubMed1991

Analysis of HMB-45 immunoreactivity in common and cellular blue nevi.

HMB-45 is generally thought of as a melanoma specific antibody; however, there are certain exceptions. It is known that most dermal nevi show no reactivity; however, the dermal nevus component within dysplastic nevi and certain Spitz nevi show positive reactivity. In order to further examine this observation, we undertook a study to examine blue nevi, both common and cellular, for the expression of HMB-45. Cases were stained with antibodies directed at both HMB-45 and S100 protein. Of 16 common blue nevi studied, 14 were positive with HMB-45, as were 6 of 6 cellular blue nevi. Staining for HMB-45 was quite variable in intensity amongst cases labelled common blue nevi. In contrast, cellular blue nevi were uniformly strongly positive. It is therefore concluded that blue nevi, including cellular blue nevi, exhibit an activated phenotype as demonstrated by HMB-45 reactivity.

Antibodies, Monoclonal↗
PubMed2001

Agminated atypical (dysplastic) nevi: case report and review of the literature.

BACKGROUND: Patients with the atypical mole syndrome have multiple dysplastic nevi that appear to be randomly distributed on certain preferred anatomical sites such as the upper back. These dysplastic nevi are thought to be acquired melanocytic nevi that begin appearing at puberty. To our knowledge, the presence of agminated atypical (dysplastic) nevi has not been reported. OBSERVATION: We describe a patient with the atypical mole syndrome who has more than 100 melanocytic nevi, many of which are clinically atypical and one of which proved to be a melanoma. Among his many melanocytic nevi is a cluster of approximately 50 nevi that are distributed in an area measuring 5 x 3 cm. The histopathologic features of these nevi are consistent with the diagnosis of "dysplastic nevus." CONCLUSIONS: To our knowledge, agminated atypical (dysplastic) nevi have not been described previously. The presence of agminated atypical (dysplastic) nevi in a patient with the atypical mole syndrome can be theorized to arise because of loss of heterozygosity.

Adult↗
PubMed1994

[Role of sun exposure on benign melanocytic nevi. A first study in populations controlled for age, sex and phenotype].

BACKGROUND: These studies were designed to assess the influence of sun exposure on nevi in white people. In order to eliminate the confounding effect of age, sex and phenotype, two parallel studies were conducted in people of the same age (17 to 24 years), sex (males) and phenotype: one in people with "red" phenotype and one in people with "dark" phenotype. RESULTS: In both groups, comparison of nevus counts on the inner and outer side of the upper extremities and comparison of mean density of nevi (number per square meter) in always-exposed and never-exposed skin show that number of nevi is higher in sun exposed areas. In both groups the density of large and atypical nevi was maximal on intermittently sun-exposed skin while the density of small nevi was maximal on always-exposed skin. The number of large nevi on intermittently-exposed skin correlated with cumulative intensive exposure during beach recreation in the red phenotype group. The number of large nevi was significantly higher in red phenotypes who repeatedly experienced severe sunburns in their first 20 years of life. CONCLUSIONS: The number of nevi at the end of the second decade is influenced by cumulative sun exposure from birth. "Traumatizing" sun exposure, which is more frequent in "red" phenotype than in "dark" one, has an influence on the number of large nevi and is therefore likely to make small nevi grow.

Adult↗