Spitzoid malignant melanoma with lymph-node metastasis. Is a copy-number loss on chromosome 6q a marker of malignancy?

The role of lymphatic mapping and sentinel node biopsy in the management of atypical and anomalous melanocytic lesions

Atypical and anomalous melanocytic lesions are tumors that cannot be determined by microscopy to be certainly benign or fully malignant. The malignant potential of these borderline lesions is unknown and logical determination of best therapy is challenging, in particular whether lymphatic mapping and sentinel node biopsy have a place in their management. Lesions that fall into this category include atypical Spitzoid lesions, atypical cellular blue nevi, combined nevi, deep penetrating nevi, ancient nevi, desmoplastic nevi, balloon cell nevi and proliferation nodules of congenital nevi. We report our experience managing patients with these problematic tumors and discuss our approaches to determining the true location of lesional cells in sentinel nodes.

Comparative genomic hybridization analysis of genetic aberrations associated with development of esophageal squamous cell carcinoma in Henan, China

AIM: To characterize cytogenetic alterations in esophageal squamous cell carcinoma (ESCC) and its metastasis.

METHODS: A total of 37 cases of primary ESCC and 15 pairs of primary ESCC tumors and their matched metastatic lymph nodes cases were enrolled from Linzhou, the high incidence area for ESCC in Henan, northern China. The comparative genomic hybridization (CGH) was applied to determine the chromosomal aberrations on the DNA extracted from the frozen ESCC and metastatic lymph node samples from these patients.

RESULTS: CGH showed chromosomal aberrations in all the cases. In 37 cases of primary ESCC, chromosomal profile of DNA copy number was characterized by frequently detected gains at 8q (29/37, 78%), 3q (24/37, 65%), 5p (19/37, 51%); and frequently detected losses at 3p (21/37, 57%), 8p and 9q (14/37, 38%). In 15 pairs of primary ESCC tumors and their matched metastatic lymph node cases, the majority of the chromosomal aberrations in both primary tumor and metastatic lymph node lesions were consistent with the primary ESCC cases, but new candidate regions of interest were also detected. The most significant finding is the gains of chromosome 6p with a minimum high-level amplification region at 6p12-6q12 in 7 metastatic lymph nodes but only in 2 corresponding primary tumors (P = 0.05) and 20p with a minimum high-level amplification region at 20p12 in 11 metastatic lymph nodes but only in 5 corresponding primary tumors (P < 0.05). Another interesting finding is the loss of chromosome 10p and 10q in 8 and 7 metastatic lymph nodes but only in 2 corresponding primary tumors (P < 0.05).

CONCLUSION: Using the CGH technique to detect chromosomal aberrations in both the primary tumor and its metastatic lymph nodes of ESCC, gains of 8q, 3q and 5p and loss of 3p, 8p, 9q and 13q were specifically implicated in ESCC in Linzhou population. Gains of 6p and 20p and loss of 10pq may contribute to the lymph node metastasis of ESCC. These findings suggest that the gains and losses of chromosomal regions may contain ESCC-related oncogenes and tumor suppressor genes and provide important theoretic information for identifying and cloning novel ESCC-related oncogenes and tumor suppressor genes.

Understanding spitzoid tumours: new insights from molecular pathology

Spitzoid tumours are a morphologically diverse group of lesions that share histological similarity to the Spitz naevus, a benign melanocytic skin tumour. Distinguishing classic Spitz naevi from cutaneous malignant melanoma is usually achievable on standard histology sections, but occasionally equivocal lesions are encountered that show features intermediate between these two entities and consequently generate considerable clinical and histopathological concern. The nomenclature and diagnostic criteria for spitzoid lesions are not standardized and this article begins by considering the adverse effect this has on our understanding of spitzoid tumour biology. Investigations of some of the hallmark features of cancer and neoplasia in spitzoid tumours are described, and the contribution of these studies to our understanding of spitzoid tumour biology is considered, along with their potential diagnostic utility. These studies compare spitzoid tumours with better-characterized melanocytic lesions, and from such comparisons assumptions concerning the biological nature of different spitzoid tumours can be made. In contrast, investigations of the mitogen-activated protein kinase (MAPK) pathway and DNA gains and losses have suggested that Spitz naevi may be genetically distinct from other melanocytic tumours. The studies that led to this conclusion are reviewed, as well as subsequent work examining whether the same applies to all spitzoid tumours. Possible explanations for the considerable inconsistencies within some of these data are explored. Finally, potential pathways of tumour progression within spitzoid lesions are considered, with an emphasis placed upon insights gained from investigations of MAPK genes and DNA gains and losses.

Differentiating spitzoid melanomas from Spitz nevi through CD99 expression

BACKGROUND

A true diagnostic marker differentiating Spitz nevi (SN) from spitzoid melanoma (sMM) has been elusive. CD99, a transmembrane glycoprotein, believed to play a role in many neoplastic processes, has yet to be investigated in this regard. Recently, the expression of CD99 has been shown in 60% of primary melanomas. Other studies exploring the expression of CD99 in melanocytic lesions have not been performed. Here, we evaluate the presence of CD99 in these two histologically difficult to differentiate entities.

METHODS

Cases of sMM were selected based on the presence of key microscopic words: spitz, spindled and/or epitheliod. In addition, all the cases of SN over the past 7 years were retrieved. Each case was stained with anti-human CD99 and analyzed for the presence of CD99 staining.

RESULTS

Fifteen of 27 cases (56%) of sMM expressed CD99 compared with only 3 of 58 cases (5%) of SN.

CONCLUSIONS

This study shows 56% of sMM and only 5% of SN express CD99. Eight of the sMM showed strong diffuse staining, a pattern not seen in any of the SN. This study does not elucidate the role that CD99 plays in these melanocytic processes; however, it does show that CD99 can be a useful tool in distinguishing sMM from SN.

Unusual histological variants of cutaneous malignant melanoma with some clinical and possible prognostic correlations

Malignant melanoma is known for the wide range of histological patterns it can assume mimicking other malignant tumors. We present a review of most of the unusual histological variants of cutaneous melanoma and describe their immunohistochemical features, associate clinical findings, and possible behavior related to the histological subtype. In addition, we propose their classification into four groups corresponding to the (1) architectural patterns; (2) cytologic features; (3) stromal changes; and (4) the possible association of these findings (i.e. architectural + cytologic features). Although most of these unusual variants have the same prognosis as conventional melanomas, with Breslow thickness and ulceration, being the most important predictor of survival in clinical stage I, some of them have a peculiar biologic behavior that the clinicians and the dermatopathologists should know in order to give melanoma patients all educational information available.

The approach to the patient with a difficult melanocytic lesion

Although most histological diagnoses are made with relative ease and with great specificity and reproducibility, there is a subset of cases in which a specific and reproducible diagnosis is difficult or even impossible to render. In the melanocytic system, these cases can be divided into two broad categories. The first category, 'superficial atypical melanocytic proliferations of uncertain significance' (SAMPUS), includes predominantly junctional melanocytic proliferations, and melanocytic proliferations that are confined to the epidermis and papillary dermis, without evidence of tumorigenic proliferation or mitotic activity there. The prognosis for cure of these lesions is excellent if they are completely excised. Such lesions may include, for example, dysplastic naevi, Spitz naevi or pigmented spindle cell naevi with a few atypical melanocytes above the dermal-epidermal junction, or with greater than average cytological atypia, or with mitoses, where the differential diagnosis of melanoma in situ is difficult or impossible to rule out. The other category, 'melanocytic tumours of uncertain malignant potential' (MELTUMP), is comprised of melanocytic proliferations that form tumours in the dermis, and are therefore potentially capable of metastasis. Examples of such lesions may include atypical Spitz naevi, deep penetrating naevi, possible naevoid melanomas, or cellular blue naevi, where because of increased mitotic activity or cytologic atypia, a diagnosis of invasive or tumorigenic melanoma cannot be ruled out. In managing such lesions, we follow two main principles. The first is to manage each lesion with therapy designed to be adequate for management of the most significant consideration in the differential diagnosis. The second principle is to make clinicians and patients specifically aware of the diagnostic difficulty in their lesion, so that management can be undertaken on a true informed consent basis.

Applications of microarrays to histopathology

High-throughput microarray technologies have the potential to impact significantly on the practice of histopathology over the coming years. Global gene expression profiling allows for a systematic search of all human genes for novel diagnostic and prognostic markers and for potential therapeutic targets. Likewise, gene copy number changes can be determined on a gene-by-gene basis using microarrays. Tissue microarrays are an efficient method to extend and validate the findings obtained from the initial 'discovery' phase of the research, done using cDNA microarrays. In addition, tissue microarrays can be used for quality assurance for immunohistochemical and in situ hybridization procedures. In this review we give a brief overview of microarray technology and research uses, and discuss potential applications of microarrays in the practice of diagnostic histopathology.