Clinical and histopathologic analyses of pigmented macular lesions on the soles of Japanese--proposal of a clinical guideline for detection of early malignant melanoma on the sole

Of 92 pigmented macular lesions on the soles of Japanese, 88 lesions were histologically confirmed to be melanocytic: 65 ordinary acquired melanocytic nevi, 9 congenital melanocytic nevi, 5 dysplastic nevi, and 5 possible and 4 definite lesions of early malignant melanomas. None of the ordinary acquired melanocytic nevi were more than 7 mm in maximum diameter. Excluding congenital melanocytic nevi, there were 8 lesions whose greatest diameters were more than 7 mm: 2 dysplastic nevi, and 2 possible and 4 definite lesions of early malignant melanoma. Judging from the data obtained in this study, we propose the following clinical guideline for the detection of early lesions of malignant melanoma on the sole. If the pigmented lesions have no possibility of being congenital melanocytic nevus, black heel, lesions of Peutz-Jeghers syndrome, or 5-FU induced lesions, measure the maximum diameters. 1) Lesions with a diameter of more than 7 mm should be excised for histological evaluation. 2) Lesions with a diameter between 6 and 7 mm should be examined histologically when they show conspicuous irregularity in shape, color and/or border or are observed on the soles of a patient older than 50.     

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.     

Relation of maximum diameters of plantar malignant melanoma to various prognostic factors and prognosis of patients

The following factors were investigated in 43 cases of plantar malignant melanoma: maximum diameters of primary lesions, Clark's subtypes, clinical stages, UICC's stages, Clark's levels of invasion, Breslow's tumor thickness, and prognosis of patients. Relation of maximum diameter of primary lesions to various prognostic factors and prognosis of the patients was analysed. It was revealed that there were no statistically significant relationships between maximum diameters and other various factors. In our series, however, all patients with plantar malignant melanoma less than 14 mm in diameter are alive without metastasis. Judging from our previous and present studies, the following two points are the most important for improving the prognosis of patients with plantar malignant melanoma: 1) Catching all pigmented lesions on the sole that are more than 7 mm in diameter and examining them histologically, if they have no possibility of being congenital melanocytic nevus or black heel. 2) Treating plantar malignant melanomas adequately before they become 14 mm in maximum diameter.     

EFFECTIVE DETECTION OF PLANTAR MALIGNANT MELANOMA

Background: As the sole of the foot is the most prevalent site of malignant melanoma in non-Caucasians, early detection of the neoplasm at this anatomical site is very important. In our previous study, we proposed a clinical guideline that acquired melanocytic lesions on the sole larger than 7 mm in maximum diameter should be examined histologically. Methods: Eighty-one Japanese patients with the complaint of plantar pigmented lesions were screened at our dermatology clinic during 3 years using the 7-mm criterion. Results: Of the total 80 melanocytic lesions on the sole, 14 lesions were larger than 7 mm in maximum diameter, excluding congenital lesions. Diagnoses of the 14 “large” lesions were as follows: advanced malignant melanoma, 8 lesions; early malignant melanoma (malignant melanoma in situ), 1 lesion; acquired melanocytic nevus, 4 lesions, and volar melanotic macule, 1 lesion. Conclusions: The present study confirmed the validity of the 7-mm criterion for the early effective detection of plantar malignant melanoma.     

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.     

Clinical diagnosis of dysplastic melanocytic nevi: A clinicopathologic correlation

A prospective, community practice-based, clinicopathologic correlation was undertaken in 165 melanocytic nevi excised from a group of forty-three patients, each patient having previously had at least one clinically suspected and histologically confirmed dysplastic melanocytic nevus. Eighty-two percent of seventy-two lesions with histologic evidence of mild dysplasia had been diagnosed correctly as such clinically. The accuracy of clinical diagnosis of moderate dysplasia was low (20%); however, all cases of severe dysplasia with or without in situ melanoma were diagnosed correctly. In 75% of all cases in which dysplasia of any degree was diagnosed clinically, histologic evidence of dysplasia was found. In order to investigate further the clinical features of these nevi, 175 color enlargements of histologically confirmed dysplastic melanocytic nevi were examined. The following clinical features were found to be most common: ill-defined border (90%), irregularly distributed pigmentation (84%), maximum diameter greater than 5.0 mm (72%), erythema (64%), and accentuated skin markings (63%). Increasing darkness and confluence of pigmentation in these dysplastic melanocytic nevi correlated with increasing severity of dysplasia. We conclude that careful clinical examination of individual melanocytic nevi will separate severe dysplasia with or without in situ melanoma from low-grade (mild or moderate) dysplasia in a high percentage of nevi from patients with the dysplastic nevus syndrome. Clinical examination will yield a diagnosis of dysplasia in approximately 75% of nevi from such patients in whom histologic evidence of dysplasia is present. Clinical examination constitutes a practical and sufficiently reliable method for the assessment of melanocytic nevi in patients with the dysplastic nevus syndrome.     

Melanocytic proliferations associated with lichen sclerosus.

OBJECTIVES: To describe the clinicopathologic features of melanocytic proliferations associated with lichen sclerosus (LS) and to compare these findings with those in controls. DESIGN: Cohort study. SETTING: Academic and private practice dermatology and dermatopathology services. PATIENTS: Cases of melanocytic proliferations associated with LS and consecutive controls with persistent (recurrent) melanocytic nevi, persistent malignant melanomas, and compound melanocytic nevi. MAIN OUTCOME MEASURES: Diagnostic criteria and disease recurrence. RESULTS: Eleven patients, all female, with a mean age of 40 years (range, 8-83 years), presented with pigmented lesions clinically suspected to be malignant melanoma or atypical melanocytic nevi affecting the vulva (7 patients), perineum (3 patients), or chest (1 patient). Lichen sclerosus was first identified in the biopsy specimen and subsequently confirmed clinically. In 10 cases, a melanocytic nevus was superimposed on LS (overlying or entrapped by sclerosis), whereas LS was found at the periphery of vulvar malignant melanoma. After complete excision, no recurrences have been reported for the melanocytic nevi in LS (mean follow-up, 29 months; range, 4-60 months). Compared with control lesions, the LS melanocytic nevi most closely resembled persistent melanocytic nevi and could be distinguished from persistent malignant melanoma histologically. Melanocytes, nevoid or malignant, proliferating contiguously with fibrotic or sclerotic collagen, contained abundant melanin, diffusely expressed HMB-45, and had a higher Ki-67 labeling index than ordinary melanocytic nevi. However, persistent malignant melanoma exhibited mitotic figures, significantly higher Ki-67 labeling index, and deep dermal HMB-45 expression compared with LS melanocytic nevi and persistent melanocytic nevi. CONCLUSIONS: Melanocytic nevi occurring in LS have features in common with persistent melanocytic nevi and can mimic malignant melanoma. An "activated" melanocytic phenotype is seen in LS melanocytic nevi, implicating a stromal-induced change.     

Multiple post-chemotherapy plantar nevi

The induction of multiple melanocytic nevi in children after chemotherapy has been documented in the literature. This situation apparently has more to do with the state of immunosuppression that is produced than with any specific agent used. We present the case of a 12-year-old girl who presented with multiple plantar melanocytic nevi after multidrug chemotherapy for acute lymphocytic leukemia. None of the lesions showed any alarming clinical signs. Although the degeneration of post-chemotherapy melanocytic nevi to melanoma has not been documented in any of the cases described, the presence of a high number of melanocytic nevi is an accepted risk factor for melanoma; thus, close clinical follow-up of these patients seems advisable.     

Follow-up of melanocytic skin lesions with digital epiluminescence microscopy: patterns of modifications observed in early melanoma, atypical nevi, and common nevi

BACKGROUND: Digital epiluminescence microscopy (DELM) has been reported to be a useful technique for the follow-up of melanocytic nevi. One of the promises of this technique is to identify modifications over time that indicate impending or incipient malignancy and to facilitate surveillance of melanocytic skin lesions, particularly in patients with multiple clinically atypical nevi. OBJECTIVE: Our purpose was to report on patterns of modifications over time observed in benign melanocytic skin lesions and melanoma. METHODS: A total of 1862 sequentially recorded DELM images of melanocytic lesions from 202 patients (mean age, 36.1 years; 54.0% female patients) with multiple clinically atypical nevi were included in the analysis. The median follow-up interval was 12. 6 months. Melanocytic lesions with substantial modifications over time (enlargement, changes in shape, regression, color changes or appearance of ELM structures known to be associated with melanoma) were excised and referred to histopathologic examination. RESULTS: A total of 75 melanocytic skin lesions (4.0%) from 52 patients (mean age, 33.3 years; 63.5% female patients) showed substantial modifications over time and were excised and referred to histopathologic examination. Eight changing lesions were histologically diagnosed as early melanomas. These lesions frequently showed focal enlargement associated with a change in shape as well as appearance of ELM structures that are known to be associated with melanoma. In contrast, the majority of benign changing lesions (common and atypical nevi) showed symmetric enlargement without substantial structural ELM changes. Six of the 8 patients in whom melanoma developed were unaware of the fact that the lesion had changed over time. CONCLUSION: We demonstrate that follow-up of melanocytic lesions with DELM helps to identify patterns of morphologic modifications typical for early melanoma. DELM may therefore serve as a useful tool to improve the surveillance of patients with multiple atypical nevi.     

Displacement of dermal solar elastosis in malignant melanoma

BACKGROUND: Ultraviolet radiation (UVR) is a major environmental causal factor for skin malignancy. In this study, we investigated the morphology of the solar elastosis (SE) band in benign and malignant melanocytic lesions. METHODS: We measured the SE band in perilesional and lesional skin of 13 melanomas (9 invasive and 4 in situ) and 11 melanocytic nevi (5 usual intradermal nevi, 4 blue nevi and 2 desmoplastic nevi) occurring in sun-exposed areas. RESULTS: The melanoma and nevus groups had similar age range, gender ratio and anatomic distribution. The mean SE thickness was 0.35 mm in melanomas and 0.29 mm in nevi (p = 0.56), indicating similar UVR exposure. There was a mean downward SE displacement (SED) of 0.43 mm in melanomas and essentially no displacement (-0.02 mm) in nevi (p < 0.005). Tumor cells and inflammatory host response were responsible for SED in melanoma. CONCLUSIONS: SED may help in the differential diagnosis of melanocytic lesions in sun-exposed areas. In melanoma, the new lesion depresses the pre-existing SE band. Conversely, the long-standing nevus co-exists with the SE band without significant displacement. Evaluation of the SE band may help to differentiate melanoma with chronic sun-induced damage as they have a distinct set of molecular alterations.     

Weight of decision-making impairs clinical assessment of melanocytic lesions

BACKGROUND AND OBJECTIVE: We studied the weight of decision-making on clinical assessment of melanocytic lesions judging benign, atypical, and malignant lesions; common mistakes; and total removal rates, comparing dermatologists with nondermatologists. METHODS: Of 11,246 histopathology specimens, 3,768 had a clinical assessment of melanocytic lesions. Histopathologic diagnosis served as the gold standard. RESULTS: Benign nevi were assessed most accurately (77%). Dermatologists assessed benign nevi better (p < .0001). The accuracy of clinical assessment in atypical nevi and melanoma was lower (23% and 42%, respectively). Seborrheic keratosis was the most common mistaken diagnosis. Complete removal of clinically benign nevi, atypical nevi, and melanoma was 84%, 90%, and 89%. Decision-making impaired clinical assessement of melanocytic lesions by 5% for dermatologists and 9% for nondermatologists. CONCLUSION: The accuracy of clinical assessment of melanocytic lesions is high for benign nevi, with dermatologists outperforming nondermatologists. Clinicians overestimated malignant potential. Complete removal was more frequent in suspicious lesions. Clinical decision-making impaired assessment by 5 to 9%.     

Comparison of pHH3, Ki-67, and survivin immunoreactivity in benign and malignant melanocytic lesions

Differentiating malignant melanoma from benign melanocytic lesions can be challenging. We undertook this study to evaluate the use of the immunohistochemical mitosis marker phospho-Histone H3 (pHH3) and the proliferation markers Ki-67 and survivin in separating malignant melanoma from benign nevi. Sixty-six melanocytic lesions (18 malignant melanomas, 8 Spitz nevi, 20 dysplastic nevi, and 20 compound nevi) were stained with antibodies to pHH3, Ki-67, and survivin. No pHH3 expression was detected in the dermis of compound and dysplastic nevi. Rare mitoses were observed in the superficial dermis in 3 of 8 Spitz nevi (37%). Staining for pHH3 was higher in malignant melanomas [average 25 per 10 high-power field (HPF), range 2-75 per 10 HPF] than in Spitz nevi (average 0.5 per 10 HPF, range 0-2 per 10 HPF) and was heterogeneously distributed in the malignant melanomas compared with a superficial dermal location in Spitz nevi. There was no cytoplasmic staining for survivin in any of the 66 melanocytic lesions and no nuclear staining in any of the benign ones. Survivin nuclear staining was present in 12 of 18 cases of malignant melanoma (67%) with an average index of 7% (range 0%-15%). In benign melanocytic lesions, the Ki-67 index was less than 5% (range 0%-4%) and staining was present close to the dermo-epidermal junction compared with an average index of 27% in melanomas (range 5%-50%) and a generally heterogeneous pattern of staining throughout the dermis. pHH3 and Ki-67 can be useful adjuncts to histopathology to separate malignant melanoma from benign nevi. pHH3 is especially useful to highlight mitoses and to rapidly assess the mitotic activity in melanocytic lesions.     

Increased Melanocytic Nevi in Patients with Inherited Ichthyoses: Report of a Previously Undescribed Association

Abstract: Ichthyosis is a heterogeneous cornification disorder. Melanocytic lesions have not been previously described in association with ichthyosis. Their clinical importance lies in the fact that they may simulate melanoma clinically and dermoscopically, as seen in epidermolysis bullosa. The objective of this study was to evaluate the clinical, dermoscopic, and histopathologic features of nevi and lentigines in 16 patients with autosomal recessive congenital ichthyosis—lamellar ichthyosis and nonbullous ichthyosiform congenital erythroderma. Patients underwent general clinical examination dermoscopy. The more suspicious lesions were excised and to histopathologic examination. Most patients (n = 13) reported no personal or familial history of melanoma or atypical nevi. All of the patients had at least five atypical melanocytic lesions. Ten of the 16 patients had at least one atypical nevus or lentigo. This study suggests that increased atypical melanocytic nevi may be a feature of long‐standing congenital ichthyoses. Whether this finding is disease‐related or a coincidental observation is difficult to ascertain. As an unequivocal discrimination from malignant melanoma in vivo is not always possible, regular clinical follow‐up of patients with ichthyosis and increased or unusual nevi is recommended.     

Immunohistochemical expression of cyclooxygenage-2 in melanocytic skin lesions

Background Several reports have shown expression of cyclooxygenase‐2 (COX‐2) in malignant skin tumors. COX‐2 has also recently been reported as a marker of malignant melanoma (MM). Objective Our aim was to investigate whether there is a difference in the immunohistochemical expression of COX‐2 between malignant and benign melanocytic lesions of the skin. Methods We selected 40 archival cases of MM including 10 cases of superficial spreading melanoma, 10 of lentigo maligna melanoma, 10 of nodular melanoma, and 10 of acral lentiginous melanoma. For comparison, we also selected 35 benign melanocytic lesions, which included 15 nonatypical nevi and 10 atypical nevi. The remaining 10 cases were Spitz nevi. COX‐2 immunohistochemical staining was performed, and intensities were assessed quantitatively. Results The MM group and the benign melanocytic nevi group showed a highly statistically significant difference in the intensity of COX‐2 expression (P < 0.0001). Staining intensity in the dermal component of MM cases also showed a tendency to increase with increasing tumor depth. By contrast, the intensity of the dermal component in the melanocytic nevi group decreased with increasing depth as the nevus cells matured from type A to type C cells. No statistical difference was noted between the MM and Spitz nevi cases (P = 0.20). Conclusions Malignant melanoma shows stronger immunohistochemical expression of COX‐2 than benign melanocytic nevi. Although COX‐2 cannot be used alone to differentiate MM from melanocytic nevi, it may serve as an aid in the differential diagnosis of melanocytic skin lesions.     

AgNOR (nucleolar organizer regions) staining in malignant melanoma.

Nucleolar organizer regions (NORs) are loops of ribosomal DNA seen in nuclei, which are demonstrable as black dots (AgNOR) in tissue sections by silver (Ag) colloid staining. The number of such AgNORs is correlated with cellular activity and is an indicator of the degree of malignancy. In this study, 76 melanocytic lesions were analyzed by AgNOR staining, and the clinical and histopathological characteristics of malignant melanoma and melanocytic nevi were considered. Although the AgNOR counts for melanocytic nevi were significantly different from those in malignant melanoma, an obvious overlap between them was detected. The number of AgNORs in melanocytic nevi per cell was usually 1 or 2. On the other hand, the number of AgNORs per malignant melanoma cell was variable. Morphologically, malignant melanoma cells often showed dispersal of AgNORs throughout the nucleus as well as multiple nucleoli containing clustered AgNORs, whereas melanocytic nevus cells tended to have a regular nucleolus with tightly clustered AgNORs. The correlation between AgNOR count and pathological staging was uncertain, but a slight correlation between AgNOR count and thickness of the primary lesion was obtained. However, the AgNOR count in malignant melanoma was not a prognostic factor for the disease. Therefore, the AgNOR method is difficult to use for differential diagnosis between benign pigmented lesions and malignant melanoma. Nonetheless, an AgNOR count of more than two per cell favors a diagnosis of malignant melanoma.     

Effect of lesion size on the diagnostic performance of dermoscopy in melanoma detection

BACKGROUND: Dermoscopy is able to correctly classify a higher number of melanomas than naked-eye examination. Little is known however about factors which may influence the diagnostic performance during practice. The aim of the study was to analyze the effect of size of the lesion on diagnostic performance of dermoscopy in melanoma detection. METHODS: Eight dermatologists examined clinical and, separately, clinical and dermoscopic (combined examination) images of 200 melanocytic lesions previously excised [64 melanomas, 24 in situ and 40 invasive (median thickness 0.30 mm) and 136 melanocytic nevi]. After examination, diagnostic performance was analyzed in accordance with the major diameter of the lesions divided into 3 groups, i.e. small (less than 6 mm), intermediate (between 6 and 9 mm) and large (10 mm or more) lesions. These groups were shown to be highly comparable concerning the microstaging of melanomas (median thickness value 0.30, 0.22 and 0.32 mm, respectively). RESULTS: Dermoscopy increased the diagnostic performance of naked-eye examination of both intermediate and large lesions [sensitivity value: +19.3 (p = 0.002) and +10.3 (p = 0.007); diagnostic accuracy value: +7.4 (p = 0.004) and +6.1 (p = 0.07)]. On the contrary, no statistically significant increase was found dealing with small lesions (sensitivity +3.7, p = 0.66; diagnostic accuracy -1.7, p = 0.55). CONCLUSIONS: The diagnostic improvement associated with the addition of dermoscopy to naked-eye examination is influenced by the size of the lesion, i.e. it is lacking with lesions up to 6 mm in diameter. The optimized use of dermoscopy in melanoma detection is obtained dealing with melanocytic lesions 6 mm in diameter or larger.     

HMB-45 staining in benign and malignant melanocytic lesions. A reflection of cellular activation.

The antibody HMB-45 used as an immunohistochemical reagent has often been labeled as a marker for melanoma, even though some benign lesions have been noted to show positive staining reactions with this reagent. Biopsy specimens from 225 benign and malignant melanocytic lesions were examined after immunoperoxidase staining for S-100 protein and HMB-45. The lesions studied included common acquired nevi, spindle cell and epithelioid cell nevi (Spitz nevi), cellular blue nevi, deep penetrating nevi, congenital nevi, nevi from hormonally reactive areas (genital), malignant melanoma, and desmoplastic malignant melanoma. A positive reaction for HMB-45 was seen in the dermal component in a high percentage of each of these types of lesions except for the common acquired nevi and the desmoplastic malignant melanomas that were uniformly negative for HMB-45 in the dermal component. HMB-45 correlates with melanosome production and thus a melanocytic origin of HMB-45-positive cells. HMB-45 may correlate best with factors that stimulate melanocytic proliferation and production of melanosomes.     

The limited specificity of histological examination in the diagnosis of dysplastic nevi

Dysplastic nevi were originally described as a distinct entity with specific clinical and histological features of importance as direct precursors of malignant melanoma and as markers of patients at increased risk of developing melanoma in the setting of familial melanoma. Nevi with the clinical and histological features described first as 'B-K moles' and later as 'dysplastic nevi' clearly do exist and do sometimes represent melanoma precursors or melanoma risk markers, but it is now recognized that most dysplastic nevi never progress to melanoma, that the histological features originally described in nevi in familial melanoma patients are poorly correlated with dysplastic nevi as they are defined clinically, and that overlapping or identical histological features are found in a variety of other melanocytic lesions including small (< 5 mm) melanocytic nevi, lentiginous nevi, atypical (dysplastic) lentiginous nevi, lentiginous melanoma, lentigo maligna and nevi in an ever-growing number of 'special sites'. This article will briefly review the evolution of our understanding of the histological range of nevi and the histological differential diagnosis of dysplastic nevi.     

Proliferation antigens in cutaneous melanocytic tumors--an immunohistochemical study comparing the transferrin receptor and the Ki 67 antigen

The cellular reactivities with the monoclonal antibodies OKT9 and Ki 67 have been demonstrated to be closely related to proliferation in various malignant neoplasms. In this study a total of 25 melanocytic skin tumors was examined immunohistochemically with both antibodies and the results were evaluated semiquantitatively for OKT9 and quantitatively for Ki 67 by stereological methods. All cases of primary and metastatic malignant melanoma expressed a strong stainability for OKT9, whereas benign melanocytic nevi were almost completely negative. Our results with the monoclonal antibody Ki 67 revealed highly significant differences in the numerical density of Ki-67-positive cells between metastatic malignant melanoma (number of positive cells: 47.0 +/- 9.2 X 10(3)/mm3), primary malignant melanoma (6.3 +/- 1.9 X 10(3)/mm3) and benign melanocytic nevi (2.2 +/- 0.7 X 10(3)/mm3). Correlation analysis between mean percentage of OKT9-positive cells and numerical density of Ki-67-positive cells revealed a significant correlation of both parameters (r = 0.58; p less than or equal to 0.05), indicating a positive relationship of OKT9 and Ki 67 expression. Especially in primary malignant melanoma, however, the amount of OKT9-positive cells considerably exceeds that of Ki-67-positive cells. The monoclonal antibodies OKT9 and Ki 67 reflect 'proliferative activity' in melanocytic skin tumors, as both are expressed in significantly higher amounts in primary and metastatic malignant melanomas. The combined application of these antibodies in cutaneous melanocytic lesions might be of diagnostic and prognostic value.     

Clinically unapparent melanocytic nevi on the prepuce

Background:  Melanocytic nevi from the genitalia are uncommon. Nevi on the vulva are much better described than nevi on male genitalia. To our knowledge, a systematic study of preputial melanocytic nevi has not been reported.
Objective:  To investigate the frequency of clinically unapparent melanocytic nevi on a series of preputial excisions.
Materials and Methods:  We undertook a prospective histologic study of the prepuce obtained in a series of 372 consecutive circumcisions for phimosis performed during the period between January 2000 and December 2002.
Results:  Incidental preputial melanocytic nevi were detected in four (1.1%) patients. Lesions were dermal in nature, most of them showed pigment in superficial dermal nests and had pseudovascular spaces. There were no cytologic atypia, mitotic figures, architectural disorder or inflammatory infiltrate. The mean (standard deviation, SD) of the maximum diameter was 1.08 (0.85) mm (range 0.34–1.79 mm). The mean age (SD) of the patients was 41.5 (4.95) years (range 29–58).
Conclusions:  Incidental melanocytic nevi, although uncommonly, can be observed in the prepuce. They are detected in adults and may pose a diagnostic challenge when they are detected in the setting of concurrent malignant melanoma.