Atypical nevi of the scalp in adolescents

BACKGROUND: A few reports in the literature point out that in special areas of the body, nevi can have peculiar pseudomelanomatous features. In our routine work, we have met few examples of atypical nevi with peculiar features on the scalp of teenagers. To evaluate the frequency and the biological behaviour of these lesions, we have conducted a complete survey on melanocytic lesions on the scalp in a significant group of patients. MATERIALS AND METHODS: Thirty-nine nevi of the scalp were from adolescents (12-18 years), 160 from adults, and 30 from children below the age of 12 years. RESULTS: About 10% of the melanocytic nevi of the scalp of adolescents have atypical cytological and architectural aspects that are different from those seen in Clark's dysplastic nevus. The most striking features were the presence of large bizarrely shaped nests scattered disorderly along the junction with follicular involvement. Other findings were pagetoid spread of cells above the junction and the discohesive pattern of the melanocytes in the nests. Mild cytological atypia was present but less significant. Such distinctive aspects are not found in nevi of the same site in adults or younger children. The general pattern of these atypical nevi of the scalp of adolescents closely recalls that of the so-called atypical nevi on special sites, i.e. nevi on mammary line, genitalia and body's folds. Despite the architectural and cytological atypia, clinical follow-up does not show any tendency to recur or proclivity to malignant behaviour. CONCLUSIONS: Despite their similarities with melanoma, the nevi with atypical features of the scalp of adolescents are probably an entirely benign entity, at least at the moment of their excision. However, although benign, the relationship of this peculiar group of nevi with melanomas developed in adulthood remains entirely unknown, and the complete excision with conservative margins seems a recommendable procedure.     

Histological features and outcome of inverted type‐A melanocytic nevi

The presence of enlarged epithelioid/spindled nests located deep in the reticular dermis of a biphasic melanocytic neoplasm can mimic melanoma arising in a pre‐existing nevus, causing over‐interpretation of malignancy. We aimed to define the clinicopathologic significance of epithelioid/spindled nests in melanocytic nevi. Retrospectively using clinical and histologic information, we characterized 121 patients with a single lesion showing epithelioid/spindled melanocytes in the reticular dermis or subcutaneous fat, surrounded by melanophages, sometimes blending in with the adnexa. The majority of nevi occurred in women in the ages of 10 to 39 years, where the most frequent presentation was a changing mole. While 78% of the lesions displayed an anatomic (Clark’s) level of IV‐V, there was no ulceration, significant regression or inflammation. Up to 2 mitoses were found in only 12% of the cases, not correlating with the severity of cytological atypia. No recurrence or metastasis occurred during 45.5 months (mean) of clinical follow up in 26 patients. Notwithstanding the deep dermal extension, these findings suggest a benign histopathology and clinical outcome. Having compared the overlapping histopathology and clinical features between deep penetrating/clonal nevus and combined nevus, we posit that “inverted type‐A nevus” might be considered a variant of the two.     

Melanocytic lesions of the genital area with attention given to atypical genital nevi

Melanocytic lesions of the genital area are rare. They arise mainly in the vulva, although they can also occur less frequently in the perineum, mons pubis and male genitalia and represent 10-12% of pigmented lesions of White women. These pigmented lesions include melanocytic nevi, lentigines, melanocytic nevi with architectural disorder and atypia of melanocytes (dysplastic nevi) and melanomas with microscopic features similar to those seen elsewhere on the body. There is a small subset of benign nevi named atypical melanocytic nevi of the genital type (AMNGT) that occur in young women, with distinctive histologic features in some cases overlapping morphologically with those of melanoma. Thus, it is important to distinguish AMNGT from melanomas in terms of prognosis and treatment. We retrieved 58 cases of genital pigmented lesions diagnosed at our hospital from 1986 to 2008 to evaluate their clinicopathologic features with especial consideration to those cases with atypical features. Thirty-two cases (55%) were common nevi, 10 (17%) lentigines, 6 (10%) melanomas, 3 (5%) dysplastic nevi and 1 blue nevus. Six cases (10%) corresponded to AMNGT and were taken from women with a median age of 21 years. All cases showed symmetry, and the melanocytic proliferation was well demarcated at the lateral margins. The junctional component was very prominent and formed by round or fusiform nests with common retraction artifact and/or cellular dyshesion or as a single cell proliferation with mild (33%) to moderate (67%) cytologic atypia, focal pagetoid spread (17%) and a benign-appearing dermal component (83%) with maturation and dense eosinophilic fibrosis in the superficial dermis. Neither nuclear atypia of melanocytes in the superficial dermis nor dermal mitoses were observed. AMNGT were excised, and no recurrences were recorded in the follow up (median 10.5 years). Therefore, it seems that there is no evidence that AMNGT are precursors of dysplastic nevi or melanomas.     

Clark's nevus

"Clark's nevi" is the name we apply to lesions that have been referred to in the past as dysplastic nevi or nevi with architectural and/or cytologic atypia. Our criteria for this histopathologic diagnosis include such architectural features as: (1) uneven distribution of melanocytes along the dermoepidermal junction; (2) irregularly spaced junctional nests that sometimes bridge between rete; and (3) ill-defined margins often characterized by a lentiginous growth pattern. If dermal nests are present, the junctional component usually extends laterally for some distance beyond the dermal nests. When there is cytologic atypia, it involves scattered melanocytes. Clark's nevi are of doubtful significance if few in number and occurring in a young patient in whom there is no family history of melanoma. When many are found in a patient with a family history of melanoma, their presence serves as a marker for dysplastic nevus syndrome (familial atypical mole-melanoma syndrome). When Clark's nevi develop in patients older than 40 or 50 years of age who have no family history of melanoma, their significance is less clear. However, they might signify a defect in those mechanisms that normally control formation and growth of melanocytic neoplasms.     

The relationship between melanocytes and peripheral nerve sheath cells (Part I): melanocytic nevus (excluding so-called "blue nevus") with peripheral nerve sheath differentiation

Among thousands of specimens of melanocytic nevi, not including giant congenital melanocytic nevus or blue nevus, 42 melanocytic nevi that showed peripheral nerve sheath differentiation were collected. The patterns of melanocytic nevi with peripheral nerve sheath differentiation may be classified into three groups: 1) "neurotized and neural nevi" with nests of "neuroid cords" and "nevic corpuscles" (the most common pattern); 2) nerve fascicle-like structures with no relation to neurotized and neural nevi; and 3) palisading melanocytes of a nevus in nests of conventional melanocytic nevi (a rare pattern). Each pattern may represent a different expression of nerve sheath differentiation in melanocytic nevi. Some melanocytic nevi with nerve fascicle-like structures show discrete structures closely resembling authentic nerve fascicles, confirming a close relationship between melanocytes and peripheral nerve sheath cells (Schwann cells and probably perineurial cells in part) and suggesting derivation of the two types of cells from common precursor cells of the neural crest and their de novo development in the dermis rather than by Abtropfung of melanocytes from the epidermis. In addition, the high prevalence of Unna, Miescher, and superficial congenital nevi in melanocytic nevi with peripheral nerve sheath differentiation suggests a different character or process for these congenital melanocytic nevi than for Clark and Spitz nevi (junctional and compound types).     

Oestrogen receptor-beta expression in melanocytic lesions

Melanomas rarely occur before puberty, have a higher death rate for males, and tend to be more invasive during pregnancy. Prior to the discovery of a second oestrogen receptor (ERbeta), studies with the initial oestrogen receptor, ERalpha, showed no obvious role for oestrogen in the pathophysiology of benign or malignant melanocytic lesions. To investigate the specific immunostaining patterns of ERalpha and ERbeta, benign nevocytic nevi, dysplastic nevi with mild, moderate and severe cytological atypia, lentigo malignas and melanomas of varying depth (Clark) and thickness (Breslow) were studied. ERbeta but not ERalpha was the predominant oestrogen receptor we found in all types of benign and malignant melanocytic lesions. The most intense ERbeta immunostaining was seen in melanocytes in dysplastic nevi with severe cytological atypia and in lentigo malignas. ERbeta expression levels also correlated with the malignant tumor microenvironment; i.e., melanocytes in proximity with keratinocytes>deeper dermal melanocytes in contact with stroma>minimally invasive melanomas>Clark Level III/IV or thick melanomas (Breslow). Discovery that ERbeta expression varies in relation to the tumor microenvironment and increasing depth of invasion suggests its possible usefulness as a surrogate marker for neoplasia and prognosis in malignant melanoma.     

Congenital pauci-melanotic cellular blue nevus

Unusual or atypical melanocytic nevi can be confused with malignant melanoma. Two patients are presented here with a rare variant of melanocytic nevus. Both were men. One was 39 years old and sought medical attention after trauma of a "congenital mole". The other was 24 years old and presented with a history of a slowly growing lesion, which had been known since childhood. In both patients, the lesion occurred on the buttock. They were dermal and superficial subcutaneous nodules measuring 1.5 and 2.3 cm in greatest dimension, respectively. The tumors were composed of densely cellular fascicles of melanocytes arranged in a lobulated growth pattern. Rare nests of small epithelioid melanocytes were also seen. No melanin pigment was seen on hematoxylin and eosin-stained sections. Focal minimal pigment was noted by Fontana-Masson stain in one case. Involvement of numerous peripheral nerve trunks by fusiform melanocytes was a prominent feature. Rare mitotic figures were seen in melanocytes [1-2 mitoses per 50 high-power fields (HPF)]. The MIB-1 labeling index was low (less than 5% of the lesional cell population was immunopositive). Both tumors were excised with negative surgical margins. One patient underwent sentinel lymph node biopsy because there was controversy regarding the biologic potential of the lesion. No melanocytic tumor deposits were found in the lymph nodes. On clinical follow up of 11 years and 18 months after complete excision, both patients are alive and well with no evidence of recurrence. We regard these lesions as congenital monophasic and pauci-melanotic variants of cellular blue nevus. The nevi are presented here to enhance our knowledge of the morphologic spectrum of melanocytic tumors and to help avoid confusion with malignant melanoma.     

Intraepidermal distribution patterns of melanocytes in the melanocytic lesions on the sole: proposed criteria for histopathologic diagnosis of plantar malignant melanoma in situ

Eighty-eight melanocytic lesions on the soles of Japanese were histologically investigated. Increased numbers of solitary melanocytes above the basal layer of the epidermis were often found in the benign melanocytic nevi on the sole: in 5 lesions of 9 congenital melanocytic nevi, 22 of 65 acquired melanocytic nevi, and 1 of 5 dysplastic nevi. In addition, a moderate degree of nuclear atypia of proliferating melanocytes was frequently observed in the benign melanocytic nevi on the sole: in 3 lesions of 9 congenital melanocytic nevi, 17 of 65 acquired melanocytic nevi, and 2 of 5 dysplastic nevi. Therefore it cannot be said that increased numbers of solitary atypical melanocytes above the basal layer is a characteristic histologic feature of early malignant melanoma in situ. Combining the intraepidermal distribution patterns of melanocytes and maximum diameter of the lesion, we propose criteria for histopathologic diagnosis of plantar malignant melanoma in situ.     

Aggressive melanoma in an infant with congenital melanocytic nevus syndrome and multiple,NRAS and BRAF mutation‐negative nodules

We report the case of a newborn boy with multinodular NRAS and BRAF mutation‐negative congenital melanocytic nevi and cerebral lesions compatible with congenital intraparenchymal melanosis. Histopathology from skin lesions showed atypical nodular melanocytic proliferation with marked melanocytic atypia and a large number of mitoses and apoptosis, indicating aggressive proliferation. The child developed several new subcutaneous tumors and multiple internal lesions, which were confirmed to be metastases, and died at 5 months of age. This case may represent an infantile melanoma developing from a giant congenital melanocytic nevus or a congenital melanoma.     

Proliferation, apoptosis, and survivin expression in a spectrum of melanocytic nevi

BACKGROUND: Apoptosis is important for maintenance of tissue homeostasis and often dysregulated in cutaneous neoplasms. The apoptosis inhibitor survivin is expressed in melanoma and non-melanoma skin cancers and benign keratinocytic lesions. Its expression has not been studied in melanocytic nevi. OBJECTIVE: We determined the expression pattern of survivin in benign melanocytic nevi in comparison to markers of proliferation and apoptosis. METHODS: Six cases of each of the following melanocytic nevi were retrieved from a dermatopathology archive: compound dysplastic nevus, intradermal nevus, compound nevus, neurotized intradermal nevus, and Spitz nevus. Survivin expression was evaluated by in situ hybridization. Apoptotic and proliferation indices were calculated by counting immunoreactive cells in terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling and proliferating cell nuclear antigen immunostained sections, respectively. RESULTS: All nevi, regardless of histologic type, expressed survivin. Compound melanocytic lesions expressed survivin in both epidermal and dermal compartments. The apoptotic rate was low for dysplastic, compound, and Spitz nevi, and apoptotic cells were not identified in any neurotized nevus. The proliferative index was highest for Spitz nevi, while all other nevi demonstrated rare positive cells. CONCLUSIONS: Survivin is consistently expressed in benign melanocytic lesions, while apoptotic cells are rarely identified, suggesting the dysregulation of apoptotic pathways with the accumulation of cells in these neoplasms.     

先天性色素痣伴增生性结节10例临床病理分析

目的:探讨先天性色素痣伴增生性结节的临床特点及组织病理特征。方法:收集第四军医大学西京皮肤医院2015—2019年经临床和病理确诊的10例先天性色素痣伴增生性结节患者的临床及病理资料,并进行回顾性分析。结果:10例患者年龄2~45岁（平均15岁）,9例增生性结节发生于婴儿,1例发生于成人。皮损位于四肢4例,头面部3例,...     

Melanocytic nevi of the auricular region: histologic characteristics and diagnostic difficulties

We examined auricular melanocytic nevi to evaluate their architectural and cytologic features. A retrospective analysis of 21 auricular melanocytic nevi was conducted during 3 years. The nevi were evaluated for cytologic atypia, architectural disorder, location of epidermal nests, pagetoid spread, growth pattern (symmetry versus asymmetry), demarcation of lateral borders, and host response (lymphocytic infiltrate and/or lamellar fibroplasia). Eleven cases (52.4%) measured at least 6 mm in greatest dimension and 6 cases (28.6%) were asymmetric. Fourteen cases (66.7%) were ill demarcated. Pagetoid spread was present in 12 cases (57.1%). Ten cases (47.6%) showed moderate to severe cytologic atypia. Nucleoli were prominent in 9 cases (42.8%). None of the cases showed mitoses or apoptotic melanocytes. Auricular melanocytic nevi, like those occurring in the acral, flexural, and genital areas, may exhibit some histologic features commonly found in melanomas. Careful histologic interpretation of these lesions is recommended.     

"Ancient" blue nevi (cellular blue nevi with degenerative stromal changes)

Ancient melanocytic nevi are benign melanocytic neoplasms that show degenerative and atypical changes, sometimes leading to a misdiagnosis of melanoma. We describe 6 patients (M:F ratio 4:2; age range, 15-84 years; median, 50 years) who presented with cellular blue nevi showing stromal changes resembling those of ancient melanocytic nevi. The lesions were located on the buttocks (4 patients) and on the trunk (2 patients) and clinically consisted of heavily pigmented nodules. Histology revealed the architectural pattern of cellular blue nevi. However, the architecture was strikingly altered by stromal changes like those seen in ancient melanocytic nevi, including increased number of large, dilated vessels with pseudoangiomatous features in 4 cases, hyaline angiopathy in 4 cases, myxoid changes, sclerosis or hyalinization of the stroma in all cases, and variable amounts of edema in 4 cases. In 2 cases, a large edematous area was present in the center of the lesion, and nests of ovoidal melanocytes and single dendritic melanocytes appeared to "float" in the stroma. Pleomorphic melanocytes were observed in all cases. Ancient blue nevi represent a morphologic variation of cellular blue nevi-Masson neuronevi with degenerative stromal changes. Recognition of these lesions can help prevent overdiagnosis of melanoma.     

Numerous,small, darkly pigmented melanocytic nevi: the cheetah phenotype

BACKGROUND: The presence of multiple atypical nevi or numerous melanocytic nevi increases the risk for the development of cutaneous melanoma. OBJECTIVE: We sought to describe a distinct clinical phenotype characterized by numerous (>100), small (< or =4 mm), darkly pigmented melanocytic nevi that are uniform in color. METHODS: Biopsy specimens from 6 patients (3 men and 3 women; age range, 44 to 81 years) with this clinical phenotype were reviewed and compared with a database of melanocytic lesions analyzed by the Yale Dermatopathology Laboratory (YDL) in the year 2000. RESULTS: Of the 6 patients, 4 had multiple primary melanomas develop (n = 2-4), ranging from in situ to 1.0 mm in depth. The other 2 patients each had 1 nevus with severe cytologic atypia. When compared with the YDL database, our patients were more likely to have the following pigmented lesions: junctional melanocytic nevi, junctional lentiginous nevi, junctional nevi with cytologic atypia, and simple lentigines (P <.001). CONCLUSIONS: The longitudinal evaluation of patients with this phenotype can be challenging because similar-appearing pigmented lesions (small and uniformly dark-brown to black) had a range of histologic diagnoses from simple lentigo to junctional lentiginous nevus to thin melanoma.     

Matrical carcinoma with prominent melanocytic hyperplasia (malignant melanocytic matricoma?) A report of two cases

Melanocytic matricoma is a recently described lesion characterized by well-circumscribed nodules composed of matrical and supramatrical cells with clustered ghost cells, and admixed pigmented dendritic melanocytes, with no cyst formation or connection to the epidermis or pre-existing hair follicles. Although variable cytologic atypia and frequent mitoses in the epithelial component may be present, given the well-defined margins and absence of tumor recurrences, these lesions were initially considered benign neoplasms, and not matrical carcinoma. Theoretically, the detection of numerous melanocytes in matrical carcinoma should not be surprising, but is in fact a very unusual feature. A case with extensive melanization of epithelial elements and only rare melanocytes has been reported. We report two cases of matrical carcinoma with prominent melanocytic hyperplasia, with emphasis on the ultrastructural and immunohistochemical features. Our cases might be considered the malignant counterpart of the so-called melanocytic matricoma.     

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.     

Architectural features in melanocytic lesions with cellular atypia

According to the quantity of single atypical melanocytes at the dermoepidermal junction 334 nevi were assigned to 3 groups: (1) with pronounced nuclear and cellular atypia (n = 73); (2) with moderate atypia (n = 127), and (3) without atypical melanocytes (n = 134). Three architectural features were almost exclusively observed in groups 1 and 2 with cellular and nuclear atypia: atypical localization of melanocytes in the epidermis, irregular distribution of melanocytes in the junctional zone and atypical nests of melanocytes. A combination of 2 or 3 of these features was seen in 76% of the nevi with pronounced cellular and nuclear atypia, in 28% of those with moderate atypia and in none of those without atypical melanocytes. Regarding 4 other criteria only minor but still statistically significant differences were found between the 3 groups of nevi. We conclude that these 4 other criteria, i.e. inflammatory infiltrate, lamellar and/or concentric fibroplasia, persisting lentiginous hyperplasia and dust-like pigment in melanocytes and nevus cells are not helpful for the diagnosis of a dysplastic nevus because of their low specificity. Minimal requirements for the diagnosis of a dysplastic nevus are suggested.     

Cellular nodules in congenital pattern nevi

BACKGROUND: The diagnosis of 'cellular dermal nodule in melanocytic nevi' is challenging, as it can simulate invasive and tumorigenic melanoma. Because cellular nodules are presumed benign, it is essential to differentiate them from true malignant melanoma arising within a nevus, which portends a poor prognosis. Although presumed benign, to date, no published long-term follow-up studies have proved the benignity of this lesion. METHODS: To better understand the clinical behavior and histological features of these lesions, we present a clinical pathological study of a cohort of 26 cases, for which we obtained clinical follow up by chart review and questionnaires. RESULTS: Clinical follow up was obtained on 16 out of 26 patients (61.5%) and ranged from 12 to 132 months (average 62.3 months). The cellular nodules in congenital pattern nevi, reported here, had an invariably benign clinical course. CONCLUSIONS: Features useful in differentiating cellular nodule from melanoma include: (1) lack of high-grade uniform cellular atypia; (2) lack of necrosis within the nodule; (3) rarity of mitoses; (4) evidence of maturation in the form of blending or transitional forms between the cells in the nodule and the adjacent nevus cells; (5) lack of pagetoid spread into the overlying epidermis; and (6) no destructive expansile growth. The difference between cellular nodule and melanoma arising from nevus can be very subtle, and it is important to emphasize that these lesions must be assessed on an individual case-by-case basis.     

Histologic features of melanocytic nevi seen in association with mycosis fungoides

BACKGROUND: Many different tumors have been reported to occur simultaneously as collision lesions. To date, no such events have been reported between mycosis fungoides (MFs) and melanocytic neoplasms. METHODS: Two cases are presented in which patches of MF were superimposed on melanocytic nevi. In addition, 967 biopsies of MF from 411 patients were identified in an 8-year retrospective database search. Patient pathology history summaries were reviewed to identify inflamed nevi, atypical nevi, and melanoma submitted for histologic evaluation from this population. RESULTS: The occurrence of MF in a congenital nevus was associated with a halo phenomenon restricted to the affected region of the nevus in one patient. In the other patient, nests of two morphologies (lymphocytic and melanocytic) in the same biopsy presented a potentially confusing histologic picture. No other cases of MF superimposed on a nevus were identified in 967 biopsies from 411 patients with a histological diagnosis of MF seen over the past 8 years. In this population, 57 biopsies of melanocytic lesions were identified from 28 patients, including three atypical nevi and three melanomas. CONCLUSIONS: The presence of MF superimposed on a nevus is rare and may lead to confounding histologic features or the development of a halo nevus phenomenon.     

Correlation between clinical atypia and histologic dysplasia in acquired melanocytic nevi.

BACKGROUND: The validity of clinical and histologic criteria in identifying dysplastic nevi is controversial. Recognition of the dysplastic nevus as a distinct clinicopathologic entity requires demonstration of significant agreement between clinical atypia and histologic dysplasia. OBJECTIVE: We attempted to determine the correlation between clinical atypia and histologic dysplasia in acquired melanocytic nevi and to evaluate the sensitivity and specificity of clinical criteria for dysplastic nevi when compared with histopathologic features. METHODS: A total of 940 acquired melanocytic nevi 3 mm in diameter or larger were selected by initially choosing clinically unequivocal dysplastic and nondysplastic nevi and then, from these, histologically unequivocal dysplastic and nondysplastic lesions. The level of concordance between clinical atypia and histologic dysplasia was estimated by kappa statistics. RESULTS: Nevi were classified as clinically dysplastic (n = 499) or nondysplastic (n = 441). On the basis of histologic features, 739 were classified as dysplastic and 201 as nondysplastic. Agreement between clinical atypia and histologic dysplasia was found in 432 nevi, that is, a sensitivity of 58.4% (3-5 mm = 27.2%, >5 mm = 69.8%). Agreement between clinical and histologic criteria on the absence of dysplasia was found in 134 nevi, a specificity of 66.6% (3-5 mm = 92.4%, >5 mm = 47.9%). The kappa value was 0.17 (3-5 mm = 0.14, >5 mm = 0.10). CONCLUSION: The limited sensitivity and specificity together with the negligible kappa value indicate a poor agreement between clinical and histologic diagnoses of dysplastic nevus. The dysplastic nevus cannot be considered a distinct clinicopathologic entity because histologic dysplasia is found in a range of nevi that may or may not show clinical atypia.