P16-CD8-Ki67 Triple Algorithm for Prediction of CDKN2A Mutations in Patients with Multiple Primary and Familial Melanoma

Melanoma, a malignant neuroectodermic tumor originating from the neural crest, presents a growing global public health challenge and is anticipated to become the second most prevalent malignancy in the USA by 2040. The CDKN2A gene, particularly p16INK4a, plays a pivotal role in inhibiting the cell cycle via the cyclin D/CDK2-pRb pathway in certain tumors. In familial melanomas (FM), 40% exhibit CDKN2A mutations affecting p16INK4a, impacting checkpoint G1, and stabilizing p53 expression. This study aims to establish a scoring system using immunohistochemical antibodies, providing a cost-saving approach to classify multiple primary melanomas (MPM) and FM patients based on their mutational status, thus mitigating genetic testing expenses. This retrospective study included 23 patients with MPM and FM, assessing the p16, CD8, and Ki67 immunohistochemical status. Analyses of each parameter and associations between their value intervals and genetic CDKN2A status were conducted. A total score of at least 9 out of 10 points per tumor defined melanomas with homozygous CDKN2A deletions, exhibiting a sensitivity of 100% and specificity of 94.11%. In conclusion, p16, CD8, and Ki67 individually serve as valuable indicators for predicting melanoma evolution. The algorithm, comprising these three immunohistochemical parameters based on their prognostic and evolutionary significance, proves to be a valuable auxiliary diagnostic tool for cost-effective prediction of mutational status in detecting multiple and familial primary melanomas with CDKN2A homozygous deletion.

Diagnostic and prognostic classification of atypical spitzoid tumours based on histology and genomic aberrations: A prospective cohort study with long-term follow-up

BACKGROUND

Histological classification of atypical spitzoid tumours (ASTs) is unreliable, and categorisation of these lesions into benign and malignant is poorly reproducible. Here, we classified ASTs based on histology and chromosomal aberrations and explored the prognostic significance of genomic aberrations in a prospective cohort with a long-term follow-up.

PATIENTS AND METHODS

Histologically equivocal ASTs from 76 patients were analysed by array comparative genomic hybridisation (aCGH). Tumours were histologically assessed by a panel of dermatopathologist before and after aCGH and classified as benign, ambiguous or malignant. Chromosomal aberrations were correlated with an outcome.

RESULTS

Chromosomal aberrations were detected in 45 (59%) of 76 ASTs (median age: 16 years, range: 0-74; median follow-up: 90 months, range: 13-153). The initial histological diagnosis was changed upon presentation of aCGH results in 36 of 76 cases (47%). The final diagnostic interpretation classified 61% of the lesions as benign, 18% as ambiguous and 21% as malignant. Positive sentinel lymph node biopsies (6+/29) occurred at similar rates in all diagnostic groups (P = 0.83) and were not associated with an unfavourable outcome. Two patients had local recurrences, but none of the patients developed metastasis beyond the sentinel lymph node.

CONCLUSIONS

All ASTs had an excellent prognosis, even in cases with worrisome morphology and chromosomal aberrations. With no distant metastasis or death in long-term follow-up of 76 patients, no correlation between chromosomal aberrations and prognosis was possible. However, it seems likely that in larger cohorts, metastases would arise in cases with complex aberrations and these patients should undergo clinical follow-up.

Mimics of melanoma in reflectance confocal microscopy

The diagnosis of melanoma is challenging for both dermatologists and oncologists. Incidence of melanoma increases at a rate of 3-7% per year. Usage of modern tools such as dermoscopy and in vivo reflectance confocal microscopy improve early diagnosis and can save a life. There are a few melanoma simulators which can cause confusion and mislead in the differential diagnosis. This study aims to present skin lesions which can be similar to melanoma in confocal microscopy and to emphasize the importance of a detailed differential diagnosis. We describe five melanocytic lesions similar to melanoma and misleading confocal features. Although in vivo reflectance confocal microscopy is very useful in differentiating melanocytic lesions, histopathology evaluation in cases of melanoma mimics is definitive.

An update on molecular alterations in melanocytic tumors with emphasis on Spitzoid lesions

Significant progress in the molecular pathology of melanocytic tumors have revealed that benign neoplasms, so-called nevi, are initiated by gain-of-function mutations in one of several primary oncogenes, such as BRAF in acquired melanocytic nevi, NRAS in congenital nevi or GNAQ/GNA11 in blue nevi, with consequent MAPK and PI3K/AKT/mTOR activation. Secondary genetic alterations overcome tumor suppressive mechanisms and allow the progression to intermediate lesions characterized by TERT-p mutation or to invasive melanomas displaying disruption of tumor suppressor genes. Currently, melanoma is molecularly regarded as four different diseases, namely BRAF, NRAS, NF1 and the "triple wild type" subtypes, which are associated with particular clinicopathological features. Melanocytic Spitzoid lesions include benign Spitz nevus, atypical Spitz tumor (AST) and Spitzoid melanoma. This is a challenging diagnostic group, particularly with regard to the distinction between AST and Spitzoid melanoma on clinical and histological grounds. Molecular analysis has identified the presence of HRAS mutation, BAP1 loss (often accompanying by BRAF mutations) or several kinase fusions in distinct categories of Spitz tumors. These aberrations account for the rapid growth characteristic of Spitz nevi. Subsequent growth is halted by various tumor suppressive mechanisms abrogation of which allow the development of AST, now better classified as low-grade melanocytic tumor. Although at present ancillary genetic techniques have not been very helpful in the prediction of biological behavior of AST, they have defined distinct tumor subsets differing with regard to biology and histology. Finally, we discuss how novel molecular markers may assist the differential diagnosis of melanoma, particularly from malignant peripheral nerve sheath tumor (MPNST). It is anticipated that the significant progress in the field of molecular pathology regarding the various types of melanocytic tumors, will eventually contribute to a more accurate histologic categorization, prediction of biologic behavior and personalized treatment.

Paediatric melanoma

Paediatric melanoma, although rare, is the most common skin cancer in children. Our current knowledge on paediatric melanoma incidence trends is expanding, as several studies have addressed this issue with conflicting results. Known risk factors for paediatric melanoma include family history of melanoma, a previous history of malignancy, large congenital nevi, numerous melanocytic nevi, sunburns, increased UV exposure and a sun-sensitive phenotype. In younger children, melanoma more often presents with atypical features, such as a changing, amelanotic or uniformly coloured, often bleeding lesion, not fulfilling in most cases the conventional ABCDE criteria. The major differential diagnoses are melanocytic nevi, proliferative nodules in congenital nevi and atypical Spitz tumours. Moreover, in the younger age group non-Caucasian children are over-represented, tumours tend to be thicker and lymph nodes are often involved. Despite the frequent diagnosis at an advanced stage, the overall survival is fair in paediatric melanoma. Specific guidelines for management of melanoma in children do not exist, and most often the disease is treated similarly to melanoma in adults.

Clinical Follow-up of Atypical Spitzoid Tumors Analyzed by Fluorescence In Situ Hybridization

Many neoplasms with spitzoid features remain enigmatic, especially those with intermediate grade features or "atypical spitzoid tumors" (ASTs). Fluorescence in situ hybridization (FISH) has emerged as a complementary technique to conventional microscopy, with certain chromosomal patterns conveying diagnostic information. In this study, we examined 36 ASTs analyzed by FISH for specific abnormalities in chromosomes 6, 9, and 11. Aberrations were detected in 11 cases, 7 of which met FISH criteria for spitzoid melanoma. These had homozygous deletion of 9p21, partial deletion of 11q13, gain of 6p25, and gain of 11q13. All 3 patients with positive sentinel lymph nodes, including one with progression beyond the sentinel lymph node, had homozygous deletion of chromosome 9p21, but there were no deaths in an average of 28 months of follow-up of these cases. Other aberrations in the chromosomal pattern of ASTs were heterozygous deletion of 9p21, partial deletion of 6p23, and tetraploidy. We found that ASTs, including those eventually diagnosed as spitzoid melanoma, had a more indolent course in our cohort than conventional malignant melanoma. Moreover, the addition of FISH results led to a more definitive diagnosis in 7 cases, 4 of which had abnormalities on FISH consistent with spitzoid melanoma.

Spitzoid melanoma of childhood: a case series and review

Spitzoid melanomas (SM) and atypical Spitz tumors (AST) are rare pediatric neoplasms. We performed a retrospective, single-institution review and report our institutional experience. We identified 10 patients (median age: 12.5 years). A sentinel node biopsy (SNB) was performed in 8/10 (80%) patients, and interestingly 7/8 (87.5%) were found to be positive for malignant cells. A complete regional lymphadenectomy was performed in all SNB-positive patients, but only 2/8 (25%) were found to have additional lymph node spread. Adjuvant therapy was administered in 5/8 SLNB-positive and 2/2 (100%) regional LN-positive cases. All patients had excellent long-term outcomes (100% survival). This report highlights the excellent outcomes associated with SNB + pediatric SM and AST.

Atypical Spitz Tumor Arising on a Congenital Linear Plaque-Type Blue Nevus: A Case Report With a Review of the Literature on Plaque-Type Blue Nevus

The plaque-type blue nevus (PTBN) is a rare variant of blue nevus, of which only a few reports are described. A nodular growth within a preexistent PTBN should always alert to the possibility of malignant transformation. The authors report the first case of an atypical Spitz tumor arising on a congenital linear PTBN in a 60-year-old woman. The diagnosis of “atypical Spitz tumor” is here used to describe a microscopic “gray zone” in which it is not possible to differentiate with adequate certainty between a Spitz nevus and a spitzoid melanoma. This report adds to and summarizes the small body of literature describing PTBN and discusses diagnostic and clinical implications.

Atypical Spitz tumors in patients younger than 18 years

BACKGROUND

Diagnosis and proper management of atypical Spitz tumors in pediatric age are still controversial.

OBJECTIVE

We sought to investigate the clinicopathological and molecular features of atypical Spitz tumors in patients aged 18 years or younger.

METHODS

We performed a retrospective clinicopathological and fluorescence in situ hybridization study on 50 pediatric atypical Spitz tumors.

RESULTS

Parameters that were significantly correlated with a diagnosis of atypical Spitz tumors over Spitz nevus included asymmetry, level IV/V, lack of maturation, solid growth, nuclear pleomorphism, high nuclear-cytoplasmic ratio, atypical and deep mitoses, and more than 6 mitoses/mm(2). In the atypical Spitz tumors group, a significantly higher mitotic rate was observed in prepuberal age (P = .04). The 4-probe fluorescence in situ hybridization melanoma assay did not discriminate atypical Spitz tumors from Spitz nevi. Heterozygous 9p21 loss was found in 3 of 37 cases and homozygous 9p21 loss in 2 of 37 cases. Only 1 child experienced a fatal outcome, showing genetic abnormalities by melanoma fluorescence in situ hybridization probe and a heterozygous 9p21 deletion.

LIMITATIONS

The limited number of adverse outcomes did not allow the prognostic analysis of single morphologic features.

CONCLUSION

Pediatric atypical Spitz tumors are associated with minimal lethal potential. Atypical Spitz tumors require complete excision and careful follow-up while our data do not support any clinical benefit for the sentinel lymph node biopsy procedure and completion lymphadenectomy.

Chromosomal copy number analysis in melanoma diagnostics

The majority of melanocytic neoplasms can be correctly diagnosed using routine histopathologic analysis. However, a significant minority of tumors have ambiguous histopathologic attributes that overlap between melanocytic nevi and melanoma. Ancillary tests that assist in distinguishing potentially lethal melanomas from benign melanocytic nevi with atypical histopathologic features are available, but still need refining.Most melanomas have chromosomal copy number aberrations, frequently involving multiple chromosomes. With rare exceptions, such anomalies are not found in melanocytic nevi. This difference formed the basis to develop assays that can help distinguish melanoma from nevi by fluorescence in situ hybridization (FISH) and comparative genomic hybridization (CGH). FISH can detect chromosomal copy number changes of a limited number of loci within individual cells. By contrast, CGH assesses copy number across the entire genome, but typically is performed on bulk cell populations so that copy number changes in individual cells or subpopulations of cells can go undetected. Both FISH and CGH have been used to provide genomic information in histopathologically ambiguous melanocytic tumors that can assist pathologists make correct diagnoses.

A genome-wide high-resolution array-CGH analysis of cutaneous melanoma and comparison of array-CGH to FISH in diagnostic evaluation

Benign melanocytic nevi and cutaneous melanomas can be difficult to differentiate by means of routine microscopic analysis. Recent evidence has suggested that cytogenomic analysis may be a useful diagnostic method for evaluation of melanocytic proliferations. We investigated the array-based comparative genomic hybridization (aCGH) platform for DNA copy number analysis of formalin-fixed, paraffin-embedded (FFPE) tissues in melanocytic tumors and compared aCGH analysis with fluorescence in situ hybridization (FISH) assays in diagnosis of melanoma. aCGH findings and FISH results were interpreted independently in a blinded fashion. Positive findings were not noted in any benign nevi at aCGH analysis, whereas substantial unbalanced genomic aberrations were revealed in 92% of melanomas. Positive results were obtained in 72% of melanomas via the four-probe FISH assay (RREB1/MYB/CEP6/CCND1). A few additional FISH studies were performed to verify some aCGH findings of focal amplification of oncogenes and homozygous deletion of tumor suppressor genes. The overall concordance in aberrations detected using the two methods was 90%. Most discrepancies were due to a minor abnormal clone identified via FISH that was below analytical sensitivity of the FFPE aCGH test. Our study demonstrated that copy number analysis of FFPE tumor samples via aCGH is a robust and reliable method in diagnosis of melanoma and that aCGH and FISH tests should be used as complementary methods to improve the accuracy of genetic evaluation of melanocytic tumors.