Fluorescence in situ hybridization as an ancillary method for the distinction of desmoplastic melanomas from sclerosing melanocytic nevi

The histopathologic distinction of desmoplastic melanomas from sclerosing (desmoplastic) melanocytic nevi can be difficult, especially when evaluating a partial or superficial biopsy. In the study reported herein, we applied and explored the use of a novel ancillary method, a four-probe fluorescence in situ hybridization (FISH) assay targeting RREB1, MYB, Cep6 and CCND1, to this diagnostic problem. Fifteen sclerosing melanocytic nevi, including desmoplastic Spitz nevi, conventional nevi with prominent stromal sclerosis and sclerotic blue nevi, as well as 15 examples of desmoplastic melanoma, were examined. None of the sclerosing melanocytic nevi showed a level of chromosomal aberrations that met FISH criteria for melanoma. Seven of the 15 desmoplastic melanomas were 'positive' (had documented chromosomal aberrations) by FISH. Thus, a positive FISH test strongly supports the diagnosis of melanoma in this context. However, in this setting a negative FISH test is of limited diagnostic value. Our findings suggest that prior reports about the high sensitivity of the FISH test for melanoma diagnosis need to be adjusted according to melanoma subtype.     

The anti-MAGE antibody B57 as a diagnostic marker in melanocytic lesions

The differentiation of melanoma from certain benign melanocytic lesions on histologic grounds alone may sometimes be difficult. The anti-MAGE antibody 57B was suggested to be a useful adjunct in differentiating melanoma from nevi. Our aim was to study MAGE immunoreactivity with B57 in benign melanocytic lesions that have not been investigated to this end so far. One hundred six benign melanocytic lesions were stained with the monoclonal antibody 57B. They included deep-penetrating nevus (n = 6), desmoplastic nevus (n = 9), halo nevus (n = 10), persistent melanocytic nevus (n = 12), common blue nevus (n = 17), cellular blue nevus (n = 8), cellular blue nevus with microalveolar pattern (n = 3), desmoplastic cellular blue nevus (n = 6), epithelioid blue nevus (n = 2), sclerotic blue nevus (n = 3), and clonal nevus (n = 30). Fifty-two lesions (49%) demonstrated various patterns of MAGE immunoreactivity, with clonal nevi and deep-penetrating nevi showing the most consistent staining. In conclusion, MAGE immunoreactivity detected by the monoclonal antibody 57B in formalin-fixed, paraffin-embedded tissue can be observed in benign melanocytic lesions, and therefore this antibody cannot be used in the differential diagnosis between melanoma and 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.     

结缔组织增生性色素痣四例临床病理分析

目的 探讨结缔组织增生性色素痣的病理学特点及鉴别诊断.方法 对4例皮肤结缔组织增生性色素痣的临床表现、组织学表现、免疫组化及荧光原位杂交(FISH)特点进行分析.结果 4例结缔组织增生性色素痣中,男2例,女2例,年龄19 ～ 30岁,平均26.5岁;皮损位于四肢3例,外阴1例.组织学特点:均为皮内痣,病变左右对称,痣细胞呈上皮样和(或)梭形,聚集成团或单个散在分布于增生的纤维组织之间,均未见淋巴细胞聚集、坏死或溃疡.免疫组化显示,3例痣细胞为S100和Melan A阳性,2例为P16阳性;Ki-67阳性指数均小于5％;2例间质细胞为凝血因子FⅫ和CD34阴性.荧光原位杂交(FISH)显示结缔组织增生性色素痣在6p25(RREB1)、6q23 (MYB)、6p11.1-q11.1(Cep6)及11q13(CCND1)4个基因位点均无拷贝数异常.结论 结缔组织增生性色素痣是一种组织学独特的良性黑素细胞痣,ki-67 、S100、Melan A、凝血因子FⅩⅢ等免疫组化染色和黑素瘤FISH检测有助于其与皮肤纤维组织细胞瘤和黑素瘤鉴别.     

Distinction of conjunctival melanocytic nevi from melanomas by fluorescence in situ hybridization

A conjunctival melanocytic nevus may on occasion be difficult to distinguish from melanoma both clinically and histopathologically. An unambiguous correct diagnosis is critical because of major differences in management and prognosis. We evaluated a fluorescence in situ hybridization (FISH) assay, which has previously been shown to be of value for the diagnosis of melanocytic nevi and melanomas of the skin, using probes targeting 6p25 (RREB1), 6q23 (MYB), 11q13 (CCND1) and centromere 6 (CEP6), for its potential to assist in the distinction of conjunctival melanocytic nevi from melanomas. Four melanocytic nevi and eight melanomas of the conjunctiva were analyzed. Two of the melanomas were diagnostically problematic because of suboptimal histopathology. None of the conjunctival melanocytic nevi showed a level of chromosomal aberrations that met FISH criteria for a diagnosis of melanoma. All eight conjunctival melanomas (six unequivocal and two suspicious lesions) met FISH criteria for melanoma. Thus, results from FISH assay targeting 6p25, 6q23, 11q13 and centromere 6 correlated well with the histopathologic diagnoses and supported the histopathologic suspicion in two problem cases. The findings encourage further exploration of this technique as an ancillary method for the work‐up of conjunctival melanocytic proliferations. Busam KJ, Fang Y, Jhanwar SC, Pulitzer MP, Marr B, Abramson DH. Distinction of conjunctival melanocytic nevi from melanomas by fluorescence in situ hybridization.     

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.     

Benign melanocytic lesions: Risk markers or precursors of cutaneous melanoma?

Background: The role of benign melanocytic lesions as precursors and not only as risk markers for the development of cutaneous melanoma is controversial.Objective: The purpose of the study was to assess the frequency of the histologic association of benign melanocytic lesions with cutaneous melanoma of a maximum thickness of 1.00 mm. The possibility that the spatial association of benign lesions with melanoma may be co-incidental was also investigated.Methods: The study subjects representing 289 cases of cutaneous melanoma of maximum thickness 1.00 mm (or less) were examined histologically for the presence of an associated benign melanocytic lesion(s), including lentiginous melanocytic proliferation; junctional, compound, or intradermal nevus; dysplastic nevus; and congenital nevus contiguous with or adjacent to the melanoma. The effects of age, tumor thickness, level of invasion, histologic type, and anatomic site on the association of benign melanocytic lesions with melanoma were assessed. In the control subjects 40 basal cell carcinomas and 38 compound nevi (not dysplastic) randomly chosen and matched for age (±1 year) and site (head/neck, trunk, upper and lower limbs) with a melanoma case were examined to assess the proportion of these cases associated with benign lesions compared with the matched melanoma cases.Results: A nevus was associated with melanoma in 51% of cases (n = 147). Of these, 82 (56%) were dysplastic nevi, 61 (41%) were common acquired nevi, and 4 (3%) were congenital nevi. Lentiginous melanocytic proliferation was present in the epidermis adjacent to 219 melanomas (75%) and in 44% of these cases (n = 97) a coexisting nevus was also present.Conclusion: The results of this study lend further support to the concept of common acquired nevi and dysplastic nevi as precursors of cutaneous melanoma. In addition, lesions diagnosed clinically as simple lentigo and solar lentigo may be important as potential precursors of melanoma, particularly in the elderly.     

Immunohistochemical expression of p16 in desmoplastic melanoma

Desmoplastic melanoma can be difficult to distinguish from desmoplastic melanocytic nevi both clinically and histopathologically. Several attempts have been made to explore the use of ancillary studies to facilitate this distinction. Prior work has suggested that immunohistochemical expression of p16 could help distinguish sclerosing Spitz nevi from desmoplastic melanomas. We re‐evaluated the expression of p16 in 22 desmoplastic melanomas (13 mixed and 9 pure desmoplastic tumors) and five desmoplastic melanocytic nevi (three desmoplastic Spitz nevi and two congenital melanocytic nevi with prominent dermal sclerosis). All desmoplastic melanocytic nevi were strongly immunoreactive for p16. Of the 22 desmoplastic melanomas, 6 tumors failed to label for p16, 10 were focally positive, but 6 tumors were diffusely immunoreactive. The latter finding is relevant, as it points to limitations in the diagnostic value of immunohistochemical staining for p16 for the diagnosis of desmoplastic melanocytic proliferations. Diffuse staining for p16 is not restricted to desmoplastic Spitz nevi but can also occur in a subset of desmoplastic melanomas, and this warrants caution in the use of this marker for diagnostic purposes.     

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.     

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.     

Desmoplastic nevus: An entity distinct from spitz nevus and blue nevus

Desmoplastic (sclerotic) nevus is an infrequently reported poorly characterized benign melanocytic proliferation, with only 4 case series published to date. To better define this nevus, we examined the clinical and histologic features of 25 lesions. Desmoplastic nevus is seen in both children and adults and can be located on the face, trunk, or extremities. There is a female predominance. Clinically, it can resemble intradermal nevus, atypical nevus, melanoma, and pigmented basal cell carcinoma. These are generally small, symmetric, and well-circumscribed lesions, averaging 3.5 mm in diameter. The most distinctive features include predominantly compound growth, a zonal configuration with greater cellularity in the superficial portion of the lesion, and a mixture of melanocytic phenotypes including type A, B, and C nevus cells, ovoid and dendritic melanocytes, and Spitzoid melanocytes. A distinctive eosinophilic stroma which either resembles that of a dermatofibroma or neurofibroma is always present. Variable amounts of melanin pigment are found in both tumor cells and macrophages, but this is not a prominent feature. Mitotic activity is exceedingly rare (1 case), and pleomorphism is minimal. These lesions are distinct from typical compound nevus, Spitz nevus, epithelioid blue nevus, and desmoplastic melanoma, to which they are often compared. Strict application of these histologic features allows definitive diagnosis of desmoplastic nevus as a distinct form of a benign melanocytic nevus.     

Dermoscopy of an acral congenital melanocytic nevus

Congenital melanocytic nevi carry a risk for malignant transformation into melanoma, therefore early detection of suspicious features is crucial to reduce mortality rates. Dermoscopy improves the early detection of melanoma while reducing the number of unnecessary excisions of benign pigmented skin lesions. Dermoscopically, congenital melanocytic nevi are often characterized by the presence of a cobblestone pattern, but to date, little is known about the dermoscopic features of acral congenital melanocytic nevi. We report an acral congenital melanocytic nevus typified by the presence of three different dermoscopic patterns that are commonly seen in acquired melanocytic nevi of palms and soles.     

Molecular cytogenetic analysis of Spitz nevi shows clear differences to melanoma

Spitz nevus is a benign neoplasm of melanocytes that can be difficult or impossible to distinguish from melanoma by clinical and histopathologic examination. We studied genomic DNA from 17 Spitz nevi by comparative genomic hybridization (CGH). Thirteen lesions showed no chromosomal aberrations, three cases had a gain involving the entire p-arm of chromosome 11, and one case showed a gain of chromosome 7q21-qter. Fluorescence in situ hybridization (FISH) on lesional tissue with a probe for the p-arm of chromosome 11 showed 6-10 p-arm signals per nucleus in those cases with a CGH-detected gain of chromosome 11p. One case with a normal CGH profile also showed increased copy number of 11p by FISH. Thus, the majority of Spitz nevi have a normal chromosomal complement at the level of CGH resolution; however some may contain gains, with 11p apparently being the most frequently involved location. These findings differ significantly from the previously reported changes in primary cutaneous melanoma, which show frequent deletions of chromosomes 9p (82%), 10q (63%), 6q (28%), and 8p (22%), as well as gains of chromosomes 7 (50%), 8 (34%), 6p (28%), 1q (25%) by CGH analysis. These clear differences in the location and frequencies of chromosomal aberrations in Spitz nevi and primary cutaneous melanomas could represent a basis for developing adjunctive techniques for refining accuracy in the difficult differential diagnosis of spitzoid melanocytic neoplasms.     

Polypoid Spitz nevus: two cases evaluated with genetic technique, prolonged follow up, and sentinel lymph node biopsy

Polypoid Spitz nevus represents a spitzoid melanocytic neoplasm that frequently has worrying and challenging histopathological details. Distinction from polypoid melanoma may not be straightforward. Two cases of polypoid Spitz nevus with striking histopathological features were studied. One case had prolonged follow up (Case 1) and one patient had undergone sentinel lymph node biopsy (Case 2), and fluorescence in situ hybridization (FISH) analysis was also completed (both cases). Follow up and genetic analysis of three control cases of polypoid melanoma is also presented. Our clinical and genetic results suggest that both the polypoid Spitz nevi were benign. The patients are alive with no evidence of disease. FISH analysis did not show abnormalities with probes tested. This is in sharp contrast with the control cases of polypoid melanoma, wherein genomic alterations were detectable. Our data indicate that the two polypoid lesions presented here are most probably benign, despite their worrying histopathological features. More cases with long-term follow up and greater numbers of DNA probes are necessary to extend this conclusion to other ambiguous melanocytic tumors.     

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.     

A case of adult-onset longitudinal melanonychia due to nail matrix compound nevus

A case of adult-onset longitudinal melanonychia caused by a compound nevus is described. Longitudinal melanonychias are mainly caused by melanocytic activation (hypermelanosis), lentigo (benign melanocytic hyperplasia), nevus, and melanoma. Nevi are more commonly seen in children than adults; however, melanocytic activation, atypical melanocytic proliferation, and melanoma are more frequent in adults. The majority of nail matrix nevi causing longitudinal melanonychia first appear in childhood and are junctional. Rarely, compound nevi are reported to cause longitudinal melanonychia in childhood.     

Significant melanocytic lesions in infancy, childhood, and adolescence

Malignant melanoma is diagnosed yearly in approximately 300 persons under age 20 in the United States. Relatively recent advances in dermatology include the recognition of lesions felt to be potential precursors of malignant melanoma. Small congenital melanocytic nevi, present in 1 per cent of all newborn infants, may have a small but definite potential for developing malignant melanoma. Furthermore, despite inconclusive data, many leading dermatologists now advocate removal of these small congenital lesions. Giant congenital melanocytic nevi, with their strong predilection for undergoing malignant change, are removed surgically at an early age, often in multistaged procedures. Dermabrasion, once felt to have a role in the treatment of giant congenital nevi, does not remove the malignant potential of these lesions. The dysplastic nevus syndrome, recognized in 1976, identifies individuals at increased risk for developing melanoma. Adolescents who have the dysplastic nevus syndrome or who are members of families with the syndrome require close medical supervision and patient education. The benign Spitz nevus, with its histologic similarity to malignant melanoma, continues to challenge the dermatopathologist and clinician. These lesions--the Spitz nevus, dysplastic nevus, congenital melanocytic nevus, and malignant melanoma--must all be actively considered when regarding the many other benign melanocytic lesions found in infancy, childhood, and adolescence.     

Melanocytic nevi with special features: clinical‐dermoscopic and reflectance confocal microscopic‐findings

Histopathology is considered the ‘gold’ standard for the diagnosis and classification of melanocytic nevi, but the widespread use of in vivo diagnostic technologies such as dermoscopy and reflectance confocal microscopy (RCM), has enriched profoundly the knowledge regarding the morphological variability in nevi. This is because most morphological observations made via these in vivo tools are closely correlated with features seen in histopathology. Dermoscopy has allowed for a more detailed classification of nevi. As such, dermoscopy identifies four main morphologic groups (i.e. globular, reticular, starburst and structureless blue nevi), one group of nevi located at special body sites (i.e. face, acral, nail) and one group of nevi with special features. This latter category consists of nevi of the former categories, which are typified by peculiar clinical‐histopathological findings. They can be subdivided into ‘melanoma simulators’ including combined nevi, recurrent nevi and sclerosing nevus with pseudomelanomatous features, ‘targetoid’ nevi (i.e. halo, cockade, irritated targetoid haemosiderotic and eczematous nevus) and uncommon histopathological variants such as desmoplastic, white dysplastic or ballon cell nevus. While the dermoscopic and RCM patterns of the former categories have been studied in detail, little is currently known about the clinical morphology of the heterogeneous group of ‘special’ nevi. In this article, we describe the clinical, dermoscopic and RCM features of ‘special’ nevi and review the current literature on this group of melanocytic proliferations.     

Molecular diagnosis of a benign proliferative nodule developing in a congenital melanocytic nevus in a 3-month-old infant

Small and intermediate congenital melanocytic nevi have a lifetime risk of developing melanoma estimated to range from 0% to 5%. Secondary benign melanocytic proliferations commonly arise in congenital melanocytic nevi; however, some are difficult to definitively distinguish from malignant melanoma based on clinical features and conventional histology. Herein, we describe the use of comparative genomic hybridization in supporting the diagnosis of a deep penetrating nevus developing within a congenital melanocytic nevus of a 3-month-old infant.     

Desmoplastic malignant melanoma on the buttock of an 18-year-old girl: differentiation from desmoplastic nevus

Melanocytic proliferation in young people may sometimes pose a diagnostic dilemma. This is particularly so when a desmoplastic component is present. Because the two main differential diagnoses, desmoplastic malignant melanoma and desmoplastic Spitz nevus, share some morphologic features, the diagnosis of desmoplastic malignant melanoma may be overlooked. Distinction between the two is important because they show completely different biological behavior. The age of patient, site of lesion, histologic findings of melanocytic atypia, neurotropism, mitosis, and maturation help to distinguish the two entities. We report a case of desmoplastic malignant melanoma occurring in the buttock of an 18-year-old Chinese girl. Histologically, it had typical features of desmoplastic malignant melanoma with junctional melanocytic atypia and prominent neurotropism. Clinical and histologic differences between desmoplastic malignant melanoma and desmoplastic Spitz nevus are reviewed. We conclude that although desmoplastic Spitz nevus occurs much more commonly in adolescents, desmoplastic malignant melanoma can occur in this age group and even in non-sunexposed skin. Microscopic findings remain the mainstay that guides the final diagnosis.