Spitz nevus versus spitzoid melanoma: diagnostic difficulties, conceptual controversies

Spitz Tumors and Melanoma in the Genomic Age: A Retrospective Look at Ackerman's Conundrum

After 25 years, "Ackerman's conundrum", namely, the distinction of benign from malignant Spitz neoplasms, remains challenging. Genomic studies have shown that most Spitz tumors harbor tyrosine and serine/threonine kinase fusions, including ALK, ROS1, NTRK1, NTRK2, NTRK3, BRAF and MAP3K8, or some mutations, such as HRAS and MAP3K8. These chromosomal abnormalities act as drivers, initiating the oncogenetic process and conferring basic bio-morphological features. Most Spitz tumors show no additional genomic alterations or few ones; others harbor a variable number of mutations, capable of conferring characteristics related to clinical behavior, including CDKN2A deletion and TERT-p mutation. Since the accumulation of mutations is gradual and progressive, tumors appear to form a bio-morphologic spectrum, in which they show a progressive increase of clinical risk and histological atypia. In this context, a binary classification Spitz nevus-melanoma appears as no longer adequate, not corresponding to the real genomic substrate of lesions. A ternary classification Spitz nevus-Spitz melanocytoma-Spitz melanoma is more adherent to the real neoplastic pathway, but some cases with intermediate ambiguous features remain difficult to diagnose. A prognostic stratification of Spitz tumors, based on the morphologic and genomic characteristics, as a complement to the diagnosis, may contribute to better treatment plans for patients.

Melanocytic tumors with spitzoid morphology: correlation of clinicopathologic features and FISH analysis

BACKGROUND

A subset of melanocytic tumors with spitzoid morphology may lead to potential inaccurate diagnosis and lack of assessment of malignancy potential. In this study, we aimed to evaluate melanocytic tumors with spitzoid morphology using conventional melanoma FISH (RREB-1, CCND1, MYB and CEP6) and 9p21 FISH (CDKN2A) probes and compare the probe results with clinical and histopathological features.

METHODS

This study is a multicentric retrospective study including three centers, İstanbul University-Cerrahpaşa, Cerrahpaşa School of Medicine, Department of Pathology, Acıbadem University, School of Medicine, Department of Pathology and ETA Pathology Laboratory. The pathology reports in archives of these three centers between 2015 and 2017 have been reviewed for cases diagnosed as atypical Spitz tumor or melanoma with Spitzoid features. These cases were selected for the study. We analyzed 39 cases of atypical Spitz tumor (AST), 10 cases of melanomas with spitzoid features for clinicopathological data and chromosomal alterations, targeting RREB-1 (6p25), CCND1 (11q13), MYB (6q23), together with 9p21 (CDKN2A), using FISH methodology.

RESULTS

Thirty out of total 49 cases showed chromosomal alterations by 4-probe melanoma FISH assay, 22 (56.4%) cases were ASTs, and 8 (80%) cases were melanomas. Eighteen out of 49 cases showed homozygote deletion by 9p21 FISH assay, 12 (30.8%) cases were ASTs, and 6 (60%) cases were melanomas. When histopathological data were compared with FISH results, a statistically significant correlation was found between 9p21 FISH positivity (homozygous deletion) and presence of deep mitosis (p < 0.05). In addition, epidermal consumption (p = 0.07) and increased mitotic activity (p = 0.05) were more frequent in cases with homozygous 9p21 deletion, but these differences did not reach statistical significance. When the clinical features were considered, there was a statistically significant correlation between 9p21 FISH positivity and the diameter (p < 0.05). There was no statistically significant correlation between melanoma FISH assay and any of the histopathological or clinical data.

DISCUSSION

These data suggest that 9p21 FISH positivity correlated with more worrisome histopathologic and clinical features, such as deep mitosis, increased mitotic activity, epidermal consumption, and larger lesion size, so these features are precious, pointing out spitzoid lesions with higher risk. However, there is a need for further studies using FISH or similar techniques in order to provide more accurate prognostic information in lesions Blank morphology.

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.

A sixteen-year single-center retrospective chart review of Spitz nevi and spitzoid neoplasms in pediatric patients

BACKGROUND

Spitzoid neoplasms in pediatric patients pose an interesting challenge for clinicians. More data on the clinical, histologic, and molecular characteristics of these lesions are necessary to distinguish features that may portend recurrence or malignant behavior to help determine future treatment guidelines in pediatric patients.

METHODS

Institutional Review Board approval was obtained from Children's Hospital of Wisconsin to conduct a retrospective analysis of spitzoid neoplasms. Patients with biopsied or excised spitzoid neoplasms between 01/01/2000 and 08/01/2016 were included. Pertinent clinical and histologic data were collected. Atypical, unusual, or diagnostically uncertain lesions were selected for re-review.

RESULTS

266 lesions from 264 patients were included. 243 were classified as benign (91.35%), 22 as atypical (8.27%), and 1 as spitzoid melanoma (0.38%). No clinical or histologic variables were found to be statistically significant between the benign Spitz, atypical Spitz, and spitzoid melanoma cohorts. No known deaths occurred.

CONCLUSION

Our findings highlight the extreme variability of spitzoid neoplasms clinically and histologically. Importantly, this study demonstrates that the vast majority of spitzoid neoplasms in pediatric populations are benign and supports conservative management of spitzoid lesions in children.

Clinical validity of a gene expression signature in diagnostically uncertain neoplasms

Aim: Evaluate the accuracy of a 23-gene expression signature in differentiating benign nevi from melanoma by comparing test results with clinical outcomes. Materials & methods: Seven dermatopathologists blinded to gene expression test results and clinical outcomes examined 181 lesions to identify diagnostically uncertain cases. Participants independently recorded diagnoses and responses to questions quantifying diagnostic certainty. Test accuracy was determined through comparison with clinical outcomes (sensitivity and percent negative agreement). Results: Overall, 125 cases fulfilled criteria for diagnostic uncertainty (69.1%; 95% CI: 61.8-75.7%). Test sensitivity and percent negative agreement in these cases were 90.4% (95% CI: 79.0-96.8%) and 95.5% (95% CI: 87.3-99.1%), respectively. Conclusion: The 23-gene expression signature has high diagnostic accuracy in diagnostically uncertain cases when evaluated against clinical outcomes.

Spitz Tumors of the Skin

Spitz tumors are melanocytic neoplasms hallmarked by large cell size, lack of high-grade atypia, and a regular architecture. Most are nonpigmented or poorly pigmented. Malignant potential ranges from absent (Spitz nevus), to fully present (spitzoid melanoma), with a further, ill-defined group of Spitz tumors with limited metastatic potential. Microscopic evaluation may prove inconclusive in some instances, resulting in a verdict of Spitz tumor of uncertain malignant potential (STUMP). STUMP is, therefore, not an entity, and should not be equated with Spitz tumors with limited metastatic potential. Novel diagnostic techniques are yielding promising results, and further evaluation is ongoing.

Spitz nevi: diverse clinical, dermatoscopic and histopathological features in childhood

BACKGROUND AND OBJECTIVES

The characterization of clinical features and biological potential of Spitz nevi has attracted a lot of interest in past decades. The aim of our paper was to describe the clinical, dermatoscopic features as well as the clinical outcome of surgically excised Spitz nevi in three different pediatric age groups.

PATIENTS AND METHODS

A retrospective study analyzing clinical features, videodermatoscopic images, histopathological diagnosis and patient outcome. The level of pigmentation was evaluated both clinically and histopathologically.

RESULTS

72 spitzoid neoplasms were excised from 71 pediatric patients. Videodermatoscopic images were available for 41 patients. The distribution of pigmentation significantly correlated with patient age: hyperpigmented lesions were rather rare in preschool children, becoming more frequent in patients aged 7 to 12 years and older than 13 years. The histopathological diagnosis of atypical Spitz nevus was uncommon. None of the patients originally diagnosed with atypical Spitz nevi developed local recurrence or metastases during subsequent follow-up.

CONCLUSIONS

Pigmented Spitz nevi were more common after 13 years of age. The study confirms other reports regarding the distribution of pigmentation patterns, and underlines the low number of atypical Spitz nevi in pediatric patients as well as their low recurrence rate during long-term follow-up.

Spitz nevi in the classic histopathological pattern--lamb in wolf`s clothing

Spitz nevus is a benign melanocytic lesion and also one of the main differential diagnosis of melanoma. A descriptive and retrospective study of surgical specimens from patients with a diagnosis of Spitz nevus was conducted at two institutions in Niterói - RJ. 32 cases were analyzed. The most frequent histological subtype was compound (60 %), with a predominance of epithelioid cells (17 cases - 53%). Pagetoid spread was observed in 21 cases (68%). Maturation of melanocytes was present in 13 cases (81%). Kamino bodies were found in eight cases (25%). Atypical melanocytes were present in 18 cases (56%). Mitoses were present in 11 cases (34%). Detailed knowledge of the classical form of Spitz nevi is essential for the differential diagnosis with melanoma. However, no single criterium is definitive in the differential diagnosis between Spitz nevus and 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 Spitzoid neoplasms: a review of potential markers of biological behavior including sentinel node biopsy

Atypical cutaneous melanocytic lesions, including those with Spitzoid features, can be difficult to categorize as benign or malignant. This can lead to suboptimal management, with potential adverse patient outcomes. Recent studies have enhanced knowledge of the molecular and genetic biology of these lesions and, combined with clinicopathological findings, is further defining their biological spectrum, classification, and behavior. Sentinel node biopsy provides important prognostic information in patients with cutaneous melanoma, but its role in the management of melanocytic lesions of uncertain malignant potential (MELTUMP) is controversial. This paper examines the role of molecular testing and sentinel node biopsy in MELTUMPs, particularly atypical Spitzoid tumors.

"Lentiginous melanoma": full-fledged melanoma or melanoma precursor?

On the basis of a critical review of published literature, it is concluded that there is as yet insufficient evidence to conclude that the melanocytic lesion, which is currently known as "lentiginous melanoma," is a full-fledged melanoma, with the capacity to metastasize to distant sites and to cause the demise of the patient. It is proposed that this lesion is better designated as "lentiginous SAMPUS," that is, a superficial atypical melanocytic proliferation of uncertain significance, with a lentiginous, or predominantly lentiginous, arrangement of the junctional component. As there is uncertainty regarding its actual metastatic potential or the likelihood of progression to melanoma NOS, the lesion should be removed completely, with free surgical margins.

A case of spitzoid melanoma with lymph node metastasis in a child

The distinction of a spitz nevus from a melanoma can be difficult and in some cases, impossible. A misdiagnosed spitz nevus can metastasize and lead to fatal outcomes, especially in children. A 5-yr-old girl presented with a 1-yr history of a solitary pinkish nodule on her left hand. On physical examination, she had a palpable left axillary lymph node. We performed biopsy and checked 3 sentinel lymph nodes (SLN) on her axillary area. The biopsy specimen showed multiple variably sized and shaped nests with large spindle or polygonal cells and SLN biopsy showed 3 of 3 lymph nodes that were metastasized. Under the diagnosis of spitzoid melanoma, she was treated with excision biopsy and complete left axillary lymph nodes were dissected. She received interferon-α2b subcutaneously at a dose of 8 MIU per day, 3 times weekly for 12 months, and shows no recurrence.

Utility of lymph node assessment for atypical spitzoid melanocytic neoplasms

BACKGROUND

Atypical spitzoid melanocytic neoplasms (ASMN) are cutaneous lesions of uncertain malignant potential, which can be difficult to distinguish from cutaneous melanoma. Sentinel lymph node (SLN) biopsy is a safe and useful prognostic tool for staging melanoma, but its role in staging ASMNs is not established nor is the significance of positive SLNs in these patients known. This study attempts to characterize the significance of nodal disease in ASMN.

METHODS

Patients with ASMNs who presented to the melanoma service from 1992 to 2007 were identified from a prospective database. Histological review was performed by two dermatopathologists. Demographic, treatment, and outcome data were reviewed.

RESULTS

A total of 58 patients with ASMNs were treated during the time analyzed; 31 (53%) underwent wide local excision and observation (WLE); 27 underwent wide excision and SLN biopsy. Median age was 24 (range, 6-60) years. Mean Breslow thickness was 2.9 (range, 0.5-10) mm. Median follow-up was 56 (range, 1-160) months. Ten of 58 (17%) patients had nodal metastasis. Four (13%) of 31 patients who underwent WLE developed nodal recurrences, and 6 of 27 (22%) patients had a positive SLN biopsy. Of patients with positive SLNs, none have recurred after undergoing completion lymphadenectomy. One patient presented with synchronous brain metastasis and inguinal lymphadenopathy and died of disease.

CONCLUSIONS

Nodal status does not seem to convey the same prognosis that it does in standard melanoma. There may be a limited ability for progression within the nodal basin in patients with these lesions. This subset of patients would benefit from genetic data complementing histologic analysis.

Pigmented lesion pathology: what you should expect from your pathologist, and what your pathologist should expect from you

The first part of this review examines the reliability of histologic diagnosis in pigmented lesions, as measured by concordance studies and medicolegal analysis. It emphasizes the role of clinicians in maximizing that reliability, by providing adequate clinical descriptions, using appropriate biopsy technique, and critically interpreting pathology reports. It identifies those entities that are especially problematic, either because they cannot be reliably recognized by the histopathologist or because their histology is a poor guide to their biologic behavior. The second part of the review is a guide to some of the more difficult and controversial pigmented lesions, including dysplastic nevus, spitzoid nevi and melanomas, cellular blue nevus, animal-type melanoma, and deep penetrating nevus.

Melanoma in pediatric, adolescent, and young adult patients

The family practitioner, pediatrician, and dermatologist all have potential roles in the primary prevention, diagnosis, and treatment of localized thin melanomas. Surgical and medical oncologists are often involved when controversy arises over the nature of the skin lesion or whether sentinel lymph node (SLN) biopsies and adjuvant therapy are to be contemplated. This overview of melanoma will deal with the primary and nodal pathology, surgery, and medical therapy of melanoma in pediatric, adolescent, and young adult patients--and will raise areas of controversy that are only recently being addressed in databases of cases from this age group.

Atypical spitzoid melanocytic tumors with positive sentinel lymph nodes in children and teenagers, and comparison with histologically unambiguous and lethal melanomas

Children and teenagers with a positive sentinel lymph node (SLN) after a prior diagnosis of an atypical spitzoid melanocytic tumor (ASMT) are usually cared for clinically in the same way as patients with melanoma. Little is known about long-term follow-up of these individuals to determine whether this practice is appropriate. To learn more about the biology of these tumors we retrospectively reviewed the clinical and pathologic findings of children and teenagers (<18 y of age at the time of diagnosis) with an ASMT, positive SLN and follow-up of at least 3 years. Their findings were compared with histologically unambiguous melanomas of children or teenagers, who had a positive SLN or died of metastatic melanoma. Eleven individuals, 6 girls and 5 boys, with primary ASMT and positive SLN were identified. The primary tumors ranged in thickness from 2.1 to 12 mm (median, 4.6 mm; mean, 5 mm). The tumor mitotic rate ranged from 1 to 10 mitoses/mm (median, 3/mm, median, 3/mm). The positive SLNs included 6 nodes with intranodal melanocytic aggregates measuring <1 mm in greatest dimension, and 5 nodes, in which the size of the melanocyte deposits was >/=1 mm. All the patients with ASMT and positive SLN remained free of disease with a median follow-up of 47 months (mean, 61 mo, range: 36 to 132 mo). In contrast, 2 of 5 patients <18 years of age with a histologically unambiguous melanoma and a positive SLN died of metastatic melanoma. The overall disease-specific mortality rate for all patients <18 years of age diagnosed with melanoma was 12%. Our findings confirm that children and teenagers with ASMTs and positive SLNs have a less aggressive clinical course than those with histologically unambiguous melanoma.

The classification of cutaneous melanoma

Forty years ago, a clinical and histological classification scheme and prognostic factors were described for cutaneous melanoma. This scheme included the subtypes superficial spreading, nodular and lentigo maligna, and prognostic factors including tumor thickness, ulceration, and mitotic activity. There have been some tweaks to the classification scheme, but these basic findings form the foundation for melanoma diagnosis and staging today. Currently, no molecular marker or target has proved reliably useful in the staging or treatment of melanoma. Measurement with a simple ruler serves as the basis for the staging of primary cutaneous melanoma, while the recognition of primary tumor mitotic activity and ulceration also remain significant factors. Recently, mutational analysis has revealed a correlation of activating mutations with the morphological descriptors from decades ago. Future classification schemes may have more power in predicting response to therapy by integrating specific genomic and intra-tumoral expression profiles with histologic findings.

Sentinel lymph node biopsy for patients with diagnostically controversial Spitzoid melanocytic tumors?

The distinction of a Spitz nevus from melanoma can be very difficult. Pathologists may disagree on whether a Spitzoid melanocytic proliferation is benign or malignant, or acknowledge uncertainty about the diagnosis. As long as melanoma is suspected or strongly considered, a clinical management plan is often adopted as if the patient had melanoma, which may include sentinel lymph node (SLN) biopsy for staging. The findings of the sentinel node may resolve the diagnostic controversy about the primary tumor, but there is also the risk for more diagnostic confusion, uncertainty, and errors. We review the arguments in favor and against SLN biopsy for patients with diagnostically controversial Spitzoid melanocytic tumors, summarize current experience, and illustrate diagnostic pitfalls. Although SLN biopsy provides prognostic information helpful for clinical trials, we caution against performing the procedure as a diagnostic adjunct.

Pigmented lesions in children: when to worry

PURPOSE OF REVIEW

Although the incidence of melanoma in adolescents and adults has risen dramatically in the past few decades, childhood melanoma remains uncommon. It is therefore important for pediatricians to be aware of the natural history and clinical spectrum of melanocytic nevi in children as well as potentially worrisome features of pigmented lesions.

RECENT FINDINGS

Recent studies have provided insight into the development, evolution and molecular bases of acquired and congenital melanocytic nevi during childhood. This review summarizes the types of melanocytic nevi that are commonly observed in children, environmental (e.g. sun exposure) and genetic (e.g. the familial atypical mole and melanoma syndrome) factors that can contribute to the development of nevi and future risk of melanoma, and phenotypic markers (e.g. numerous acquired nevi or the 'red hair phenotype') that signal the need for periodic total-body cutaneous examinations. Current concepts of the risks associated with congenital melanocytic nevi of different sizes and strategies for the management of various types of nevi (including congenital, blue and Spitz nevi) are presented, and data on the clinical presentations and biologic behavior of prepubertal melanoma are discussed.

SUMMARY

Clinical and molecular investigations have helped to better understand the characteristics of melanocytic nevi and define pathways of melanocytic tumorigenesis.