Immunoperoxidase technique modified by counterstain with azure B as a diagnostic aid in evaluating heavily pigmented melanocytic neoplasms

Heavily-pigmented melanocytic neoplasms are difficult to evaluate on routine hematoxylin and eosin stained slides because pigmented melanocytes are difficult to distinguish from the numerous melanophages that are usually seen in the background of these lesions. Immunoperoxidase staining for S100 protein or HMB-45 antibody using diaminobenzidine (DAB) as chromogen, which forms a brown product, does not adequately distinguish melanocytes from melanophages. We modified this technique by replacing hematoxylin as the counterstain with azure B, which stains melanin green-blue. Thus, positive melanocytes appear brown while melanin granules in their cytoplasm are green-blue. However, negative melanophages only stain green-blue. This technique is useful in evaluating heavily pigmented melanocytic lesions such as malignant melanomas, melanosis of regressing malignant melanoma, residual malignant melanoma in areas of granulation tissue with melanophages, blue nevi, pigmented spindle cell variant of Spitz's nevi and combined nevi.     

Compound blue nevus: a variant of blue nevus with an additional junctional dendritic component. A clinical, histopathologic, and immunohistochemical study of six cases

We studied six cases of heavily pigmented melanocytic lesions with features of blue nevi within the dermis, but with an additional junctional dendritic component. This compound variant of blue nevus is an uncommon lesion that has not been previously identified as a distinct histologic entity. Immunoperoxidase staining for S100 protein and counterstaining with azure B distinguished the presence of melanocytes among numerous melanophages within the dermis. The compound variant of blue nevus can be distinguished histologically from combined blue nevus, pigmented spindle cell nevus, malignant melanoma, and melanosis due to a regressed malignant melanoma. The six lesions were from three men and three women whose ages ranged from 11 to 51 years (mean, 31 years). Three lesions were located on the trunk, two on the extremities, and one on the head. After a mean follow-up period of 47 months (range, 38 to 58 months), there was no evidence of recurrence.     

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.     

Genital lentigines and melanocytic nevi with superimposed lichen sclerosus: a diagnostic challenge

BACKGROUND: Benign pigmented lesions of the genitalia, such as genital lentigines and melanocytic nevi, often show clinical and histopathologic features highly suggestive of malignant melanoma (MM). Superimposed changes of lichen sclerosus (LS) may cause real concern and lead to an erroneous diagnosis of MM. OBJECTIVE: This study was performed to assess clinicopathologic characteristics of genital lentigines and melanocytic nevi with associated LS. METHODS: We performed a retrospective review of 5 cases. RESULTS: Histopathologic sections of the 2 cases of genital lentigines with concurrent changes of LS showed a lichenoid lymphocytic infiltrate and pigment incontinence with melanophages in a fibrosed papillary dermis, features reminiscent of completely regressed MM. The 3 cases of genital melanocytic nevi and superimposed LS were sharply circumscribed, relatively symmetric, but revealed confluent nests varying in size and shape and pagetoid upward spread of melanocytic nests and single melanocytes. Changes of LS extended beyond the melanocytic proliferation. CONCLUSION: Genital lentigines and melanocytic nevi with associated LS may show features that mimic MM.     

Inflammatory cellular infiltrates in melanocytic nevi.

We examined 1,054 melanocytic nevi [137 (13%) simple lentigines, 158 (15%) junctional nevi, 337 (32%) compound nevi, and 422 (40%) dermal nevi] for the presence of lymphohistiocytic infiltrates. The following criteria were evaluated: age and sex of the patient, location, histological type, horizontal and vertical diameter, increase of melanocytes in the basal layer of the epidermis, increase of melanophages in the papillary dermis, melanin content of keratinocytes, and melanin content of nevus cells. Lymphohistiocytic infiltrates were measured semiquantitatively; their presence within the center, in the lateral margins, or both was also determined. The results were analyzed statistically by means of chi-square tests and univariate and multivariate analyses. We found that 824 lesions (78%) were associated with a lymphohistiocytic infiltrate; whereas 230 (22%) were not. This infiltrate was weak in 273 cases (33%), moderate in 411 cases (50%), pronounced in 130 cases (16%), and very strong in 10 cases (1%). Multivariate analyses revealed that the only criteria associated with the presence of lymphohistiocytic infiltrates were the increase of melanocytes in the basal layer and the vertical thickness in compound nevi. All other parameters were statistically insignificant. We conclude that melanocytic nevi with a junctional hyperplasia of melanocytes--i.e., mostly early stages such as simple lentigines, junctional nevi, and superficial compound nevi--are often associated with a moderate to pronounced cellular stromal reaction. Their presence may reflect the appearance of antigens on proliferating melanocytes. It may also represent a stromal reaction to necrotic tumor cells and keratinocytes within the dermoepidermal junction. These findings rule out any relationship to an increase of melanin pigment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Solitary small active junctional nevi in juvenile patients

Solitary small very dark and papular pigmented nevi, less than 4 mm, are seen commonly in the second decade of life and have a distinctive histologic pattern. Microscopically these lesions show abundant intraepidermal melanin, included within the keratin layer, and proliferating single melanocytes or nevus cell nests. Prominent nucleoli in the melanocytic cells, occasional mitoses, and the invariable presence of moderate numbers of dermal melanophages and lymphocytes indicated the activity of the pathologic process. The benignity of the lesions in nine patients is supported by a benign course over a one- to three-year evaluation period after limited excisional biopsy procedures. The clinical and pathologic evidence of activity in these nevi suggests yet another possible precursor of malignant melanoma. The B-K mole syndrome and the dysplastic nevi syndrome differ from these cases both clinically and histologically.     

Circumscribed dermal melanoses. Classification and histologic features

Dermal melanosis is caused by deposition of melanin in melanophages or by free melanin in the dermis or in dermal melanocytes. Circumscribed dermal melanoses can be congenital or acquired and at times are nevoid in distribution. Bilateral nevus of Ota-like lesions and blue macules recently have been described in association with progressive systemic sclerosis. Macular amyloidosis and friction melanosis are also acquired dermal melanoses. It is important to distinguish dermal melanoses caused by the presence of melanocytes in the dermis from those produced by the presence of melanin free within the dermis. Clinically, the two different processes may have very similar appearances. Treatments for circumscribed dermal melanoses include cosmetics, cryotherapy, dermabrasion, or, rarely, skin grafts.     

Animal‐type melanoma – tumor cell invasion of dermal lymphatics and molecular identification of lymph node metastasis

Animal‐type melanoma (ATM) represents a rare subtype within the wide spectrum of melanocytic tumors. Clinically, ATM lesions appear as sharply demarcated, brown, black and dark blue pigmented nodules, which show grey‐white surface elements on dermatoscopy. The tumor is restricted to the dermis and arranged in irregular fascicles, which are composed of spindle‐shaped and epithelioid melanocytes. Moderate tumor cell pleomorphism, mitoses and apoptotic cells all suggest a malignant process. Abundant, finely dispersed melanin pigment within tumor cells as well as numerous melanophages are strongly suggestive of ATM. Even though locoregional lymph node metastases are frequently found at diagnosis, the course of ATM is generally benign. Specific molecular changes may be detected in melanocytes from lesions and lymph nodes on fluorescence in situ hybridization (FISH). Such findings strongly indicate the malignant potential of ATM. The peculiar biology of ATM, as a moderately malignant tumor, is reflected in a new histopathological classification within the spectrum of dermal borderline melanocytic tumors (BMT).     

Evaluation of dermoscopic and histopathologic features and their correlations in pigmented basal cell carcinomas

BACKGROUND: Because of their clinical similarities, pigmented basal cell carcinomas (BCCs) can be confused with melanocytic pigmented lesions especially with melanoma. Since special dermoscopic features have been described for pigmented BCCs, dermoscopy is accepted as a useful tool for the diagnosis of pigmented BCCs. OBJECTIVE: To investigate dermoscopic and corresponding histopathologic features of BCCs and to evaluate their correlations in pigmented BCCs. METHODS: In this study, 32 pigmented BCCs in 30 patients whose diagnoses were confirmed with clinical and histopathologic features were included. Before the histopathologic evaluation, the lesions were analysed for dermoscopic features. Histopathologic correlations of dermoscopic features of BCCs and the localization of pigment accumulation in tumour mass were investigated. RESULTS: In addition to ulceration, large grey-blue ovoid nests, multiple grey-blue globules, maple leaf areas and arborizing telangiectasia; dermoscopically yellow-brown, whitish-yellow, and black-dark brown colour showed statistically significant correlation with their histopathologic counterparts (P < 0.05). Whitish veil, which is among dermoscopic features of BCCs, did not show significant correlation with its histopathologic counterpart (P > 0.05). It was histopathologically determined that pigmentation is found within the tumour mass as well as in the tumour stroma and in the hyperplastic epidermal melanocytes. CONCLUSIONS: Ulceration, large grey-blue ovoid nests, multiple grey-blue globules, maple leaf-like areas and arborizing telangiectasia, which are specific dermoscopic features for the diagnosis of pigmented BCC, were found to correlate with their histopathologic counterparts. In conclusion, dermoscopy can be described as a valuable tool for the diagnosis of pigmented basal cell carcinomas.     

Correlation of dermoscopic structures of melanocytic lesions to reflectance confocal microscopy

OBJECTIVE: To determine the utility of reflectance confocal microscopy (RCM) in the in vivo evaluation of dermoscopic structures of melanocytic lesions. DESIGN: For each described dermoscopic feature, we evaluated by RCM at least 2 melanocytic lesions. A digital camera connected to the confocal computer enabled direct analysis of the dermoscopic structures. To ascertain precision of correlation, the orientation of the dermoscopic and RCM images were compared using a superimposed grid. SETTING: Dermatology clinic specializing in pigmented lesions. Patients Eleven patients with melanocytic lesions, including 2 melanomas, 1 Spitz nevus, 7 dysplastic nevi, and 1 compound nevus. Main Outcome Measure Direct correlation of structures seen using dermoscopy with those seen using RCM. RESULTS: There was a good correlation between the global dermoscopic pattern and findings on the 4 x 4-mm mosaic of confocal images at the level of the dermoepidermal junction. The atypical network correlated with variability in the size and shape of dermal papillae. Globules corresponded with aggregates of bright cells, and darker shades of brown on dermoscopy appeared brighter on RCM. In peripheral streaks, RCM showed dense aggregates of pleomorphic cells of variable brightness and ill-defined cellular borders. These aggregates were continuous with the bright mesh that composed the central bulk of the lesion. A blue-white veil correlated with disruption of the rimmed papillae meshlike pattern and sometimes with the presence of bright cells corresponding to melanophages. CONCLUSION: Correlating dermoscopic structures to RCM features is possible and a necessary step toward understanding the potential benefits of RCM in the clinical setting.     

Dermoscopy for the Pediatric Dermatologist Part III: Dermoscopy of Melanocytic Lesions

Melanocytic nevi encompass a variety of lesions, including blue, Spitz, congenital, and acquired nevi. These nevi can occasionally manifest clinical morphologies resembling melanoma, and the presence of such nevi in children can elicit anxiety in patients, parents, and clinicians. Dermoscopy has been shown to increase the diagnostic accuracy for melanoma and to help differentiate melanoma from nevi, ultimately aiding in the decision‐making process as to whether to perform a biopsy. Dermoscopy is the perfect instrument to use during the evaluation of pigmented skin lesions in children because it is painless and provides important information for the clinician that can assist in formulating appropriate management decisions. This review highlights the most common benign dermoscopic patterns encountered in nevi and discuss the 10 most common dermoscopic structures seen in melanomas. Lesions manifesting a benign dermoscopic pattern and lacking any melanoma‐specific structures do not need to be excised and can safely be monitored. In contrast, melanomas will invariably deviate from the benign nevus patterns and will usually manifest at least 1 of the 10 melanoma‐specific structures: atypical network, negative network, streaks, crystalline structures, atypical dots and globules, irregular blotch, blue‐white veil, regression structures, peripheral brown structureless areas, and atypical vessels. It is important to be cognizant of the fact that melanomas in childhood usually do not manifest the clinical ABCD features. Instead, they are often symmetric, amelanotic, nodular lesions. Although the clinical appearance may not be alarming, with dermoscopy they will invariably manifest at least one melanoma‐specific structure, the most common being atypical vascular structures and crystalline structures.     

Expression of ligands to NKp46 in benign and malignant melanocytes

Human melanoma cell lines were shown to express ligands for the natural cytotoxicity receptor, NKp46, expressed by natural killer (NK) cells. We aimed to examine the expression of ligands for NKp46 by various primary human melanocytic cells and melanocytic lesions. Sections from primary nevi and melanomas were tested for expression of NKp46 ligands employing chimeric NKp46-Fc for staining. The melanocytes present in the reticular dermis were negative for NKp46 ligands in common nevi; in malignant melanocytic lesions, the deeper melanocytes were focally positive. In dermoepidermal junction of all melanocytic lesions, the melanocytes showed enhanced expression of NKp46 ligands. Melanophages in all lesions were consistently positive for NKp46 ligands. These observations establish the expression of NKp46 ligands by primary-transformed melanocytes. Normal melanocytes did not express ligands to NKp46. Therefore, the results show (i) a correlation between the malignant potential of the lesion and the expression of NKp46 ligands in the reticular dermis, and (ii) enhanced expression of NKp46 ligands in the active proliferation zone (dermoepidermal junction) of nevi and melanomas. Ligands to NKp46 were expressed on the membrane and within the cells. The physiological role of NKp46 ligands in the progression of malignancy within melanocytic lesions should be explored further.     

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.     

Automatic differentiation of melanoma from melanocytic nevi with multispectral digital dermoscopy: a feasibility study

BACKGROUND: Differentiation of melanoma from melanocytic nevi is difficult even for skin cancer specialists. This motivates interest in computer-assisted analysis of lesion images. OBJECTIVE: Our purpose was to offer fully automatic differentiation of melanoma from dysplastic and other melanocytic nevi through multispectral digital dermoscopy. METHOD: At 4 clinical centers, images were taken of pigmented lesions suspected of being melanoma before biopsy. Ten gray-level (MelaFind) images of each lesion were acquired, each in a different portion of the visible and near-infrared spectrum. The images of 63 melanomas (33 invasive, 30 in situ) and 183 melanocytic nevi (of which 111 were dysplastic) were processed automatically through a computer expert system to separate melanomas from nevi. The expert system used either a linear or a nonlinear classifier. The "gold standard" for training and testing these classifiers was concordant diagnosis by two dermatopathologists. RESULTS: On resubstitution, 100% sensitivity was achieved at 85% specificity with a 13-parameter linear classifier and 100%/73% with a 12-parameter nonlinear classifier. Under leave-one-out cross-validation, the linear classifier gave 100%/84% (sensitivity/specificity), whereas the nonlinear classifier gave 95%/68%. Infrared image features were significant, as were features based on wavelet analysis. CONCLUSION: Automatic differentiation of invasive and in situ melanomas from melanocytic nevi is feasible, through multispectral digital dermoscopy.     

Novel spot-like pigmentary pattern detected by high-resolution epiluminescence microscopy

BACKGROUND: Epiluminescence light microscopy (ELM) can be improved with enhanced optical resolution. OBJECTIVE: High-resolution ELM was performed by placing a standard light microscope on the skin surface for visualization of further details. METHODS: 25 melanocytic nevi and 14 melanomas with a globular pattern were investigated and examined histologically. RESULTS: A new spotty substructure was detected, namely individual pigmented spots of 5-10 micro m in diameter located within peripheral brown globules. Clinicopathologic correlation showed these spots to correspond with individual pigmented melanocytes (IPMs) within nests of melanocytes. IPMs were seen in 9/25 melanocytic nevi and in none of 14 melanomas. CONCLUSION: Their origin may be a physiologic, UV-dependent pigment induction suggesting that they may represent a benign ELM pattern.     

Early acral melanoma in situ: correlation between the parallel ridge pattern on dermoscopy and microscopic features

In non-white populations, acral skin is the most prevalent site of malignant melanoma. Early melanomas of this anatomic site are often misdiagnosed as melanocytic nevi, which are not uncommon on acral skin. In fact, clinical and/or histopathological features of melanocytic nevi occasionally mimic those of early acral melanoma and vice versa, and thus differentiation of early acral melanoma from melanocytic nevus is sometimes very difficult for clinicians as well as for histopathologists. Our dermoscopic investigation has revealed that the parallel ridge pattern, a band-like pigmentation on the ridges of the skin markings, is highly specific to malignant melanoma in situ on acral volar skin. In the present study, we reviewed 22 acral melanocytic lesions that showed the parallel ridge pattern on dermoscopy but had very subtle clinical and/or histopathological presentations. We diagnosed 20 of them as early melanoma in situ by careful histopathological examination, which revealed histopathological features very similar to those seen in macular portions of overt acral melanoma, but fundamentally different from features found in melanocytic nevi on acral skin. In correspondence with their dermoscopic pattern, in these early lesions of acral melanomas, proliferation of solitary arranged melanocytes was mainly detected in the crista profunda intermedia, the epidermal rete ridge underlying the ridge of the skin marking. The two remaining lesions were diagnosed as possible cases of acquired melanocytic nevus because of the formation of well-demarcated nests of melanocytes in the epidermal rete ridges. We propose that a finding of preferential proliferation of solitary arranged melanocytes in the crista profunda intermedia is an important clue for the histopathological diagnosis of early phases of acral melanoma.     

Melanocytic tumors with intraepidermal melanophages: a report of five cases with review of 231 archived cutaneous melanocytic tumors

Dermal melanophages are frequently encountered in both benign melanocytic nevi and malignant melanoma. In contrast, intraepidermal melanophages (IEM) are under‐recognized in melanocytic lesions and their biologic significance is not understood. Herein, we report the clinical and histopathologic features of five melanocytic lesions featuring IEM encountered prospectively in our dermatopathology practice at the University of Chicago. Two hundred and thirty‐one (231) archived skin primary melanocytic proliferations were also investigated retrospectively in a de‐identified, archival teaching set collection. Nineteen of 231 of the archived cases were positive for IEM. Among the total 24 IEM‐positive cases (5 prospective and 19 archived cases), 13 were categorized as Spitz nevi (p < 0.0001) and 3 as atypical Spitz tumors (p = 0.0152). Fourteen of 24 cases with IEM also exhibited intracorneal melanocytes (p < 0.0001). IEM are evidently not rare, especially in spitzoid melanocytic neoplasms. IEM in our series were significantly correlated with intracorneal melanocytosis, possibly indicating an association between IEM and suprabasal melanocytosis and/or transepidermal elimination of melanocytes.     

Spitzoid melanoma: dermoscopic report and diagnostic discussion

We present a case of a 16-year-old young man who came for a dermatologic appointment due to acne. He presented a pigmented asymptomatic lesion on the back of his right thigh. Dermoscopic examination revealed uncommon aspects, highly suspect of nodular melanoma, in particular a blue-whitish veil, striae and asymmetric globules. The lesion was promptly removed and the material referred for histopathologic examination. Microscopic findings showed an atypical spitzoid tumor, compatible with spitzoid melanoma. In this report, the importance of dermoscopy as an auxiliary method in the early diagnosis of cutaneous melanomas is emphasized. Its daily use by the dermatologist is an important tool in the decision-making process in cases of urgent removal of suspect lesions.