Cutaneous Metastases of Malignant Melanoma: A Clinicopathologic Study of 192 Cases With Emphasis on the Morphologic Spectrum

Dermatoscopic patterns of cutaneous metastases: A multicentre cross-sectional study of the International Dermoscopy Society

BACKGROUND

The detection of cutaneous metastases (CMs) from various primary tumours represents a diagnostic challenge.

OBJECTIVES

Our aim was to evaluate the general characteristics and dermatoscopic features of CMs from different primary tumours.

METHODS

Retrospective, multicentre, descriptive, cross-sectional study of biopsy-proven CMs.

RESULTS

We included 583 patients (247 females, median age: 64 years, 25%-75% percentiles: 54-74 years) with 632 CMs, of which 52.2% (n = 330) were local, and 26.7% (n = 169) were distant. The most common primary tumours were melanomas (n = 474) and breast cancer (n = 59). Most non-melanoma CMs were non-pigmented (n = 151, 95.6%). Of 169 distant metastases, 54 (32.0%) appeared on the head and neck region. On dermatoscopy, pigmented melanoma metastases were frequently structureless blue (63.6%, n = 201), while amelanotic metastases were typified by linear serpentine vessels and a white structureless pattern. No significant difference was found between amelanotic melanoma metastases and CMs of other primary tumours.

CONCLUSIONS

The head and neck area is a common site for distant CMs. Our study confirms that most pigmented melanoma metastasis are structureless blue on dermatoscopy and may mimic blue nevi. Amelanotic metastases are typified by linear serpentine vessels and a white structureless pattern, regardless of the primary tumour.

Metastasis to hypopharynx from epidermotropic metastatic malignant melanoma

Previous reports proposed the concept and criteria of epidermotropic metastatic malignant melanoma (EMMM): (a) dermal involvement equal to or broader than the epidermal involvement, (b) atypical melanocytes within the dermis, (c) thinning of the epidermis, (d) widening of the papillary dermis with an epithelial collarette, and (e) vascular invasion of atypical melanocytes. However, it remains unclear whether EMMM also involves the mucosal epithelium. In this case, the patient was diagnosed with EMMM based on the histopathological findings of the patient's multiple skin lesions and clinical course. The patient also developed metastasis to the hypopharynx. Although histopathological findings of the lesion suggested the possibility of melanoma in situ, as the lesion included atypical melanocytes in the mucosal epithelium, the clinical course supported the diagnosis of hypopharyngeal metastasis from EMMM. This case suggests that EMMM may have epitheliotropic features not only in the skin but also in the mucosa.

Lymphangitic Melanomatosis: Case Report of Intralymphatic Spread of Melanoma in a 66-year-old Man

ABSTRACT

Melanoma with lymphatic invasion has been associated with increased risk of metastasis, but the mechanisms and clinical implications are poorly understood. Although current reports have documented angiotropic spread of melanoma and suggest lymphatic spread of melanoma to increase the likelihood of metastasis, to our knowledge, lymphangitic metastatic melanoma resembling cutaneous carcinomatosis or presenting with facial hyperpigmentation has not been described. In this case report, we describe extensive cutaneous intralymphatic spread of melanoma, or lymphangitic melanomatosis, producing macular skin pigmentation in a 66-year-old man.

An unusual case of metastatic melanoma in subcutaneous tissue presenting as a solitary cystic mass with fluid levels

Malignant melanoma is a common and often aggressive neoplasm of the skin arising from melanocytes. Metastatic melanoma is known for its diverse clinical manifestations, and can present with atypical features prior to diagnosis of the primary lesion, which can pose a diagnostic challenge. We report a rare case of metastatic melanoma in a 67 year-old male who presented with a painless, enlarging mass in the right axilla over a 4 week period. Ultrasound and magnetic resonance imaging (MRI) scans revealed a well-defined solitary, cystic appearing lesion in the right axilla with a distinct fluid-fluid level. An ultrasound guided biopsy of the lesion diagnosed a metastatic melanoma. While haemorrhagic distant metastases are a well-recognised complication of malignant melanoma, particularly in the brain and lung, soft tissue metastases presenting with fluid-fluid levels is not well described in the literature. The case highlights the importance of considering the differential of melanoma metastasis when encountered with such a lesion and importance of ultrasound guided biopsy for histopathological confirmation, as the imaging features can mimic that of a haemorrhagic soft tissue sarcoma, the management of which differs substantially from that of melanoma.

Cutaneous Malignant Melanoma With Rhabdomyosarcomatous Dedifferentiation: an Immunohistological and Molecular Case Study With Literature Review

ABSTRACT

Cutaneous malignant melanoma can show a wide range of cytomorphological variability, in particular exhibiting a rhabdoid appearance is not uncommon in melanoma cells; however, the phenomenon of "dedifferentiation" with loss of melanocytic immunohistochemical properties and expression of skeletal muscle immunomarkers is exceedingly rare. Owing to the rarity of such melanomas, their clinicopathological features and molecular profile remain largely unknown. In this report, we describe the clinical, immunomorphological, and molecular features of melanomas with rhabdomyosarcomatous dedifferentiation by presenting a new case and exploring the literature for the previously reported cases.

BRAF V600E immunohistochemistry as a useful tool in the diagnosis of melanomas with ambiguous morphologies and immunophenotypes

We report three melanoma cases in which BRAF V600E immunohistochemistry (IHC) was valuable for diagnosis. Patient 1: In a patient with a history of primary melanoma on the chest and metastatic melanoma to right breast after undergoing multiple local and systemic therapies, a lung metastasis exhibited chondroid differentiation, aberrant myofibroblastic marker expression, and rare pancytokeratin positivity, without melanocytic marker expression. Patient 2: After targeted and immunotherapy for primary melanoma on the scalp as well as regional and distant metastatic melanoma, an omental metastasis showed CDX2-positive glandular structures that were negative for melanocytic markers. It was initially misdiagnosed as primary gastrointestinal adenocarcinoma. Patient 3: A patient with history of melanoma showing epithelioid morphology on the right thigh presented with multiple soft tissue nodules on skin, lymph nodes and internal organs after being lost to follow-up for 4 years. A biopsy specimen from the right thigh showed spindled cells with scattered pancytokeratin cocktail positivity and ambiguous staining for melanocytic markers. For melanomas with ambiguous morphologies and/or immunophenotypes in each of the three patients, BRAF V600E expression by IHC was maintained in both primary and metastatic melanoma specimens examined. These cases highlight the utility of BRAF V600E IHC in the diagnosis of melanoma.

Metastatic melanoma and rare melanoma variants: a review

The histopathological diagnosis of melanoma is fraught with potential pitfalls. In the setting of cutaneous metastatic melanoma, it is important to recognise the various histological patterns that can be encountered from the more common to the rare, including epidermotropic, folliculotropic, naevoid, and blue naevus-like. In addition, melanoma is notorious for phenotypic plasticity. Thus, there are many different subtypes and cytomorphological variations that can be difficult to recognise as melanoma, particularly in the recurrent or metastatic setting. Select melanoma variants including primary dermal, clear cell, plasmacytoid, signet ring cell, small cell, myxoid, rhabdoid, and dedifferentiated melanoma will be discussed, in addition to composite melanocytic neoplasms. This review is intended to remind the practitioner of key concepts of metastatic disease and select rare melanoma variants, while providing practical guidelines for accurate diagnosis.

A rare case of melanoma erysipeloides

Malignant melanoma presenting as an inflammatory skin metastasis has been described but is an exceedingly rare phenomenon. We report a case of inflammatory metastasis of cutaneous melanoma (CM).

Metastatic Melanoma to a Neurofibroma

ABSTRACT

We present an extraordinary case of metastatic cutaneous melanoma to a pre-existing neurofibroma in a 75-year-old man with a history of primary invasive melanoma in an anatomically close vicinity. Histological examination of the metastatic melanoma showed a well-circumscribed intradermal nodule of frankly malignant epithelioid melanocytes without an intraepidermal component, surrounded and sharply demarcated from a diffuse spindle cell proliferation with morphological features of a neurofibroma. The spindle cell component showed bland cytologic features, with no mitotic activity or lymphocytic inflammation and no features of malignancy. By immunohistochemistry, both components expressed S100, while HMB45 positivity and complete loss of p16 were only observed in the epithelioid cells. The morphologically distinct areas were analyzed by fluorescent in situ hybridization, which demonstrated an abnormal profile (gain of RREB1 and homozygous loss of CDKN2A) in the epithelioid nodule; however, no abnormalities were detected in the spindle cell component. Next-generation sequencing showed somatic NRAS and PTEN mutations in the melanoma cells only. The overall molecular findings supported the immunomorphological diagnosis of metastatic melanoma within a neurofibroma over the potential differential diagnosis of melanoma with a neurofibroma-like spindle/desmoplastic component.

Balloon Cell Melanoma: Presentation of Four Cases with a Comprehensive Review of the Literature

BACKGROUND

balloon cell melanoma represents less than 1% of all histological forms of malignant melanoma and represents a diagnostic challenge for the dermatopathologist.

METHODS

in this paper we present our cases of BCM found in our daily practice from 1 January 2008 to 31 December 2021, and we conduct a review of the literature relating to this entity in the period from the first description, 1970, to early 2022.

RESULTS

four cases of melanoma balloon cell have been extrapolated from our electronic database, while in the review of the literature we have identified 115 cases of patients with primary and/or metastatic BCM.

CONCLUSIONS

we believe that future studies with numerous case series are essential not only to increase the knowledge of the pathophysiology of this neoplasm but also to correctly evaluate the response of BCM patients to new oncological therapies.

Mitotically Active Nevus and Nevoid Melanoma: A Clinicopathological and Molecular Study

ABSTRACT

The distinction between nevoid melanoma and a mitotically active nevus can be challenging at the microscopic level. In this study, we performed cytogenetic testing on a cohort of 25 mitotically active melanocytic proliferations resembling common melanocytic nevus from 25 patients. Based on cytogenetic findings, the lesions were classified as "nevoid melanoma" (n = 13) or "mitotically active nevus" (n = 12). Subsequently, we compared the clinicopathological features between these 2 groups. Nevoid melanomas occurred in older patients (P = 0.007); however, there were no significant differences in gender, size, or anatomical distribution between the 2 groups. Histologically, deep/marginal mitoses (P = 0.006), lack of maturation with depth (P = 0.036), and pseudo-maturation (P = 0.006) were significantly more common in nevoid melanomas. Immunohistochemically, complete loss of p16 was an important divisive feature (P = 0.0004), seen in 70% of nevoid melanomas, and highly correlated with loss of CDKN2A gene (chromosome 9p21). Our findings suggest that such reproducible immunomorphological differences can be of value in distinguishing nevoid melanoma from mitotically active nevus. Nevoid melanomas demonstrated a spectrum of chromosomal aberrations similar to those seen in common subtypes of melanoma, which can serve as a powerful adjunct diagnostic tool in morphologically challenging lesions.

Balloon cell melanoma: a systematic review

Balloon cell melanoma (BCM) is a rare presentation of malignant melanoma characterized by large, foamy melanocytes lacking pigmentation. This is a comprehensive review of the clinical, dermoscopic, and histological features among BCM cases reported in the literature. A systematic review of all case reports and series published since 1970 was conducted via MEDLINE, Embase, and Web of Science, using "balloon cell melanoma" and synonymous search terms. Our systematic search identified 76 cases (49% male, 51% female) of BCM in the literature. The mean age at presentation was 57.81 years. Prior skin cancer, particularly melanoma (47%), accounted for 58% of pertinent medical history. Prominent clinical exam findings included raised (46%), ulcerated (73%) lesions larger than 1 cm (68%) in the lower extremities (35%). Median Breslow thickness of primary BCM cases was 2.5 mm. Hairpin vessels (75%) and structureless architecture (75%) were predominant on dermoscopy. Notable histopathology included large (47%), vacuolated (58%) cells with foamy cytoplasm (62%) and conspicuous nucleoli (27%). Positive S-100 immunohistochemistry (73%) was most frequently employed to diagnose BCM. We observed 47% primary and 53% metastatic BCM cases. Of metastatic BCMs, balloon cells in the primary lesion were unknown in 48%, devoid in 33%, and present in 20% of cases. All metastases displayed predominant balloon cell morphology. BCM may represent an advanced phase in the progression of malignant melanoma. Improved awareness of BCM characteristics among clinicians may reduce the risk of misdiagnoses.

Dedifferentiated and Undifferentiated Melanomas: Report of 35 New Cases With Literature Review and Proposal of Diagnostic Criteria

Dedifferentiated melanoma (DM) and undifferentiated melanoma (UM) is defined as a primary or metastatic melanoma showing transition between conventional and undifferentiated components (DM) or lacking histologic and immunophenotypic features of melanoma altogether (UM). The latter is impossible to verify as melanoma by conventional diagnostic tools alone. We herein describe our experience with 35 unpublished cases to expand on their morphologic, phenotypic, and genotypic spectrum, along with a review of 50 previously reported cases (total: 85) to establish the diagnostic criteria. By definition, the dedifferentiated/undifferentiated component lacked expression of 5 routinely used melanoma markers (S100, SOX10, Melan-A, HMB45, Pan-melanoma). Initial diagnoses (known in 66 cases) were undifferentiated/unclassified pleomorphic sarcoma (n=30), unclassified epithelioid malignancy (n=7), pleomorphic rhabdomyosarcoma (n=5), other specific sarcoma types (n=6), poorly differentiated carcinoma (n=2), collision tumor (n=2), atypical fibroxanthoma (n=2), and reactive osteochondromatous lesion (n=1). In only 11 cases (16.6%) was a diagnosis of melanoma considered. Three main categories were identified: The largest group (n=56) comprised patients with a history of verified previous melanoma who presented with metastatic DM or UM. Axillary or inguinal lymph nodes, soft tissue, bone, and lung were mainly affected. A melanoma-compatible mutation was detected in 35 of 48 (73%) evaluable cases: BRAF (n=20; 40.8%), and NRAS (n=15; 30.6%). The second group (n=15) had clinicopathologic features similar to group 1, but a melanoma history was lacking. Axillary lymph nodes (n=6) was the major site in this group followed by the lung, soft tissue, and multiple site involvement. For this group, NRAS mutation was much more frequent (n=9; 60%) than BRAF (n=3; 20%) and NF1 (n=1; 6.6%). The third category (n=14) comprised primary DM (12) or UM (2). A melanoma-compatible mutation was detected in only 7 cases: BRAF (n=2), NF1 (n=2), NRAS (n=2), and KIT exon 11 (n=1). This extended follow-up study highlights the high phenotypic plasticity of DM/UM and indicates significant underrecognition of this aggressive disease among general surgical pathologists. The major clues to the diagnosis of DM and UM are: (1) presence of minimal differentiated clone in DM, (2) earlier history of melanoma, (3) undifferentiated histology that does not fit any defined entity, (4) locations at sites that are unusual for undifferentiated/unclassified pleomorphic sarcoma (axilla, inguinal, neck, digestive system, etc.), (5) unusual multifocal disease typical of melanoma spread, (6) detection of a melanoma-compatible gene mutation, and (7) absence of another genuine primary (eg, anaplastic carcinoma) in other organs.

"Puffy shirt appearance": Cell crowding at low magnification may represent nevoid melanoma

BACKGROUND

Melanoma, particularly nevoid melanoma, can masquerade as benign. Helpful differentiating features include nuclear pleomorphism, atypia, prominent nucleoli, absent maturation, and increased mitotic figures. These can be subtle and easily missed unless carefully sought. Thus, the "puffy shirt appearance" concept was born from a Seinfeld episode in which the namesake character unintentionally agreed to wear a pirate-like puffy shirt. Consequently, he found himself out of place, sporting an outfit with "too much shirt in too little space". Similarly, at low-power, nevoid melanoma appears to have "too many cells in too little space". This is more pronounced and easier to appreciate when there is an associated nevus, where crowded, subtly malignant melanocytes stand out from the evenly distributed, more spaced out benign melanocytes.

METHODS

Twelve practicing dermatopathologists familiar with the puffy shirt concept in the context of melanoma were surveyed.

RESULTS

Hundred percent of participants found it most helpful as a triaging tool, prompting additional work up including higher magnification evaluation, additional levels, consultation, and/or immunohistochemistry.

CONCLUSIONS

The crowded cells in the "puffy shirt appearance" catch the eye and should provoke a more thorough inspection of the lesion. This sign is not pathognomonic for melanoma, but prompts more careful evaluation and helps prevent misdiagnosis.

Cutaneous metastases: A great imitator

Neoplastic cells originating from a primary cancer can uncommonly spread to the skin, where they suggest a poor prognosis for the patient. In women, melanoma, breast, ovarian, oral cavity, and lung are the most common primary sources; in men, melanoma, lung, colon, and squamous cell carcinoma of the head and neck predominate. The classic presentation of cutaneous metastases is a firm, painless, flesh-colored to an erythematous dermal nodule (or nodules); however, several other presentations, including inflammatory, cicatricial, and bullous lesions, have been reported. Cutaneous metastases may also mimic benign conditions such as lipomas, hemangiomas, or cellulitis. A high degree of clinical suspicion is necessary, and the diagnosis is confirmed by biopsy, which may also be used to establish the primary malignancy if unknown, as the histopathologic appearance of the metastatic tissue may mimic the primary tumor. Treatments include excision of the metastases, chemotherapy, immunotherapy, radiation, and/or palliative care.

Immunization With the CSF-470 Vaccine Plus BCG and rhGM-CSF Induced in a Cutaneous Melanoma Patient a TCRβ Repertoire Found at Vaccination Site and Tumor Infiltrating Lymphocytes That Persisted in Blood

The CSF-470 cellular vaccine plus BCG and rhGM-CSF increased distant metastases-free survival in cutaneous melanoma patients stages IIB-IIC-III relative to medium dose IFN-α2b (CASVAC-0401 study). Patient-045 developed a mature vaccination site (VAC-SITE) and a regional cutaneous metastasis (C-MTS), which were excised during the protocol, remaining disease-free 36 months from vaccination start. CDR3-TCRβ repertoire sequencing in PBMC and tissue samples, along with skin-DTH score and IFN-γ ELISPOT assay, were performed to analyze the T-cell immune response dynamics throughout the immunization protocol. Histopathological analysis of the VAC-SITE revealed a highly-inflamed granulomatous structure encircled by CD11c+ nested-clusters, brisk CD8+ and scarce FOXP3+, lymphocytes with numerous Langhans multinucleated-giant-cells and macrophages. A large tumor-regression area fulfilled the C-MTS with brisk lymphocyte infiltration, mainly composed of CD8+PD1+ T-cells, CD20+ B-cells, and scarce FOXP3+ cells. Increasing DTH score and IFN-γ ELISPOT assay signal against the CSF-470 vaccine-lysate was evidenced throughout immunization. TCRβ repertoire analysis revealed for the first time the presence of common clonotypes between a VAC-SITE and a C-MTS; most of them persisted in blood by the end of the immunization protocol. In vitro boost with vaccine-lysate revealed the expansion of persistent clones that infiltrated the VAC-SITE and/or the C-MTS; other persistent clones expanded in the patient's blood as well. We propose that expansion of such persistent clonotypes might derive from two different although complementary mechanisms: the proliferation of specific clones as well as the expansion of redundant clones, which increased the number of nucleotide rearrangements per clonotype, suggesting a functional antigenic selection. In this patient, immunization with the CSF-470 vaccine plus BCG and rhGM-CSF induced a T-cell repertoire at the VAC-SITE that was able to infiltrate an emerging C-MTS, which resulted in the expansion of a T-cell repertoire that persisted in blood by the end of the 2-year treatment.

Dermoscopy of cutaneous melanoma metastases: A color-based pattern classification

Dermoscopic studies about cutaneous metastases of malignant melanoma (CMMM) are few. Our objective was to analyze the dermoscopic features of CMMM and propose a new dermoscopic pattern classification based on color pigmentation and some specific dermoscopic features. A retrospective evaluation of 150 dermoscopic images of CMMM taken from 40 patients was performed. One hundred CMMM images were individually evaluated by six dermatologists in order to classify them according to four dermoscopic patterns: (i) blue pattern; (ii) pink pattern; (iii) brown pattern; and (iv) mixed pattern. One hundred and fifty dermoscopic images including 50 CMMM and 100 benign lesions were evaluated by five dermatologists to calculate the accuracy of these patterns in the recognition of CMMM. An intra- and interobserver reproducibility agreement study between all different dermoscopic pattern classifications was performed. Seventy-five percent of our cases of CMMM showed a monochromatic pattern. Light brown pigmented halo, peripheral gray spots and polymorphic atypical vessels were the most significant focal dermoscopic structures. The reproducibility of the color-based dermoscopic pattern classification was superior to previous dermoscopic pattern classification. In summary, a dermoscopic pattern classification based on color pigmentation and some specific dermoscopic features may be useful in recognizing early cutaneous melanoma metastasis. Multicentric studies are recommended in order to lower the impact of interobserver variability.

Epidemiologic and Histopathologic Characterization of Cutaneous Metastases in Patients Who Visited 2 Hospitals in Santiago de Chile Between 2005 and 2017

BACKGROUND AND OBJECTIVE

Cutaneous metastases (CMs) account for 2% of skin tumors and their incidence varies between 0.7% and 9% in patients with cancer. The objective of this study was to describe and analyze the demographic, clinical, and histopathologic characteristics of CM in patients who visited 2 hospitals in the Santiago de Chile metropolitan region.

MATERIAL AND METHOD

We performed a retrospective, descriptive, analytical, observational, cross-sectional study. We reviewed the pathology reports, patient records, pathology slides, and dates of death for diagnosed cases of CM from the anatomic pathology departments of 2 hospitals in the Santiago de Chile metropolitan region between 2015 and 2017.

RESULTS

Ninety-six patients with CM were included in the study; 60.42% were women and 39.58% were men. The mean (SD) age was 67.95 (13.74) years, with a range of 28 to 96 years. The most common primary tumor was melanoma in 27.08% of cases (n=26), followed by breast cancer (18.75%, n=18), and adenocarcinoma (15.63%, n=15). The median time between diagnosis of the tumor and cutaneous metastasis was 9 months. Patients with CM of melanoma had a higher survival rate than patients with metastasis of other primary tumors (P<.05). A histopathologic study of 91 slides showed that diffuse infiltration of the tissue with tumor cells was the most common pattern and vascular invasion was rare.

CONCLUSIONS

The results are similar to those found worldwide. CM is a rare manifestation of internal tumors. It presents mainly at an advanced age and is equally prevalent in both sexes.

Morphological classification of melanoma metastasis with reflectance confocal microscopy

BACKGROUND

Cutaneous malignant melanoma metastases differential diagnosis is challenging, as clinical and dermoscopic features can simulate primary melanoma or other benign or malignant skin neoplasms, and in-vivo reflectance confocal microscopy could assist. Our aim was to identify specific reflectance confocal microscopy features for cutaneous malignant melanoma metastases, and epidermal and dermal involvement.

METHODS

A retrospective, multicentre observational study of lesions with proven cutaneous malignant melanoma metastases diagnosis between January 2005 and December 2016. Lesions were retrospectively assessed according to morphological features observed at reflectance confocal microscopy. Potential homogeneous subgroups of epidermal or dermal involvement were investigated with cluster analysis.

RESULTS

Cutaneous malignant melanoma metastases (51 lesions in 29 patients) exhibited different frequencies of features according to metastasis dermoscopy patterns. Lesions classified at dermoscopy with nevus-like globular and non-globular patterns were more likely to be epidermotropic, showing characteristics of epidermal and dermal involvement at reflectance confocal microscopy. Other dermoscopy pattern classifications were more likely to be dermotropic, showing characteristics od dermal involvement at reflectance confocal microscopy. Distinguishing features at reflectance confocal microscopy included irregular (78%) and altered (63%) epidermis, pagetoid infiltration (51%), disarranged junctional architecture (63%), non-edged papillae (76%), dense and sparse, and cerebriform nests in the upper dermis (74%), and vascularity (51%). Cluster analysis identified three groups, which were retrospectively correlated with histopathological diagnoses of dermotropic and epidermotropic diagnoses (P < 0.001). The third cluster represents lesions with deep dermis morphological changes, which were too deep for evaluation with reflectance confocal microscopy.

CONCLUSIONS

Specific reflectance confocal microscopy features of cutaneous malignant melanoma metastases for correct diagnosis, and subtype diagnosis, seem achievable in most cases where morphological alterations are located above the deep dermis.

Expression of HMB45, MelanA and SOX10 is rare in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancer (NSCLC) and melanoma are frequent entities in routine diagnostics. Whereas the differential diagnosis is usually straight forward based on histomorphology, it can be challenging in poorly differentiated tumors as melanoma may mimic various histological patterns. Distinction of the two entities is of outmost importance as both are treated differently. HMB45 and MelanA are recommended immunohistological markers for melanoma in this scenario. SOX10 has been described as an additional marker for melanoma. However, comprehensive large-scale data about the expression of melanoma markers in NSCLC tumor tissue specimen are lacking so far.

METHODS

Therefore, we analyzed the expression of these markers in 1085 NSCLC tumor tissue samples. Tissue microarrays of NSCLC cases were immunohistochemically stained for HMB45, MelanA, and SOX10. Positivity of a marker was defined as ≥1% positive tumor cells.

RESULTS

In 1027 NSCLC tumor tissue samples all melanoma as well as conventional immunohistochemical markers for NSCLC could be evaluated. HMB45, MelanA, and SOX10 were positive in 1 (< 1%), 0 (0%) and 5 (< 1%) cases. The HMB45 positive case showed co-expression of SOX10 and was classified as large cell carcinoma. Three out of five SOX10 positive cases were SqCC and one case was an adenosquamous carcinoma.

CONCLUSIONS

Expression of HMB45, MelanA and SOX10 is evident but exceedingly rare in NSCLC cases. Together with conventional immunomarkers a respective marker panel allows a clear-cut differential diagnosis even in poorly differentiated tumors.

A Practical Approach to the Diagnosis of Melanocytic Lesions

CONTEXT.—

Melanocytic lesions are common in routine surgical pathology. Although the majority of these lesions can be confidently diagnosed using well-established morphologic criteria, there is a significant subset of lesions that can be diagnostically difficult. These can be a source of anxiety for patients, clinicians, and pathologists, and the potential consequences of a missed diagnosis of melanoma are serious.

OBJECTIVE.—

To provide a practical approach to the diagnosis of melanocytic lesions, including classic problem areas as well as suggestions for common challenges and appropriate incorporation of ancillary molecular techniques.

DATA SOURCES.—

Literature search using PubMed and Google Scholar, incorporating numerous search terms relevant to the particular section, combined with contemporaneous texts and lessons from personal experience.

CONCLUSIONS.—

Although a subset of melanocytic lesions can be diagnostically challenging, the combination of a methodical approach to histologic assessment, knowledge of potential diagnostic pitfalls, opinions from trusted colleagues, and judicious use of ancillary techniques can help the pathologist navigate this difficult area.

Comprehensive histopathological comparison of epidermotropic/dermal metastatic melanoma and primary nodular melanoma

AIMS

Metastatic melanoma involving the epidermis and/or upper dermis may show significant histological overlap with primary cutaneous melanoma, especially the nodular subtype. Proper histopathological classification is crucial to appropriate staging and management, but is often challenging. The aim of this study was to identify helpful histopathological features for differentiating epidermotropic/dermal metastatic melanoma (EDMM) and primary nodular melanoma (PNM).

METHODS AND RESULTS

A cohort of EDMMs (n = 74) and PNMs (n = 75) was retrospectively reviewed for various histopathological features, and the data were compared between groups by the use of univariate analysis. Features significantly associated with EDMM included a tumour size of <2 mm, an absence of tumour-infiltrating lymphocytes and plasma cells, monomorphism, and involvement of adnexal epithelium. Features associated with PNM included a polypoid (exophytic) configuration, prominent tumour-infiltrating plasma cells (TIPs), a tumour size of >10 mm, ulceration, epidermal collarettes, a higher mitotic rate, necrosis, multiple phenotypes, significant pleomorphism, and lichenoid inflammation. In multivariate analysis, a logistic regression model including large tumour size, ulceration, prominent TIPs, lichenoid inflammation and epidermal collarettes was highly predictive of PNM. Six (8%) EDMMs from three patients showed an 'epidermal-only' or 'epidermal-predominant' pattern closely simulating in-situ or microinvasive melanoma. Two of these cases were tested by fluorescence in-situ hybridisation, which confirmed clonal relationships with their corresponding primary melanomas.

CONCLUSIONS

This is the first comprehensive histopathological comparison of EDMM and PNM. Recognition of the above histopathological associations should aid in the correct classification and staging of cutaneous melanoma. Epidermotropic metastatic melanomas may occasionally show an epidermal-only/epidermal-predominant pattern; accurate diagnosis requires prudent clinical correlation and, when necessary, ancillary molecular tests.

Cutaneous Metastatic Melanoma Resembling a Halo Nevus, in the Setting of PD-1 Inhibition

Malignant melanoma is a common source of cutaneous metastases and can occasionally adopt a histological appearance which mimics a primary melanocytic lesion, either benign or malignant. The authors describe a case of new cutaneous deposits of metastatic melanoma in a 70-year-old woman with a prominent admixed lymphocytic infiltrate, imparting a striking resemblance to a halo nevus. The authors believe this appearance was a direct reflection of treatment with pembrolizumab, a humanized antibody against the immune checkpoint inhibitor programmed death-1. With increasing use of immune-modulating drugs, this potential histological mimic may be seen more frequently in the future.

Metastatic Malignant Melanoma With Complete Loss of Differentiation Markers (Undifferentiated/Dedifferentiated Melanoma): Analysis of 14 Patients Emphasizing Phenotypic Plasticity and the Value of Molecular Testing as Surrogate Diagnostic Marker

Metastatic malignant melanoma is notorious for its phenotypic diversity and loss of differentiation markers. We herein summarized our experience with 14 metastatic melanomas showing complete loss of immunohistochemical melanocytic markers (with or without heterologous differentiation). Patients included 11 men and 3 women aged 24 to 78 years (median, 67 y). Thirteen patients had histologically confirmed primary skin melanoma, and 1 had metastatic melanoma of unknown primary. Undifferentiated metastasis was diagnosed synchronous to primary tumor (n=1), following skin melanoma by 3 months to 9 years (n=11) and preceding it by 1 year (n=1). Sites of undifferentiated metastases were axillary (3), inguinal (1), or submandibular (1) lymph nodes, digestive tract (2), bone/soft tissue (2), lung/pleura (2), and disseminated (n=3). Histology of metastases mimicked undifferentiated pleomorphic or spindle cell sarcoma with variable myxoid and giant cell areas (n=10) and cytokeratin-positive undifferentiated small cell sarcoma (n=1). Three cases showed heterologous dedifferentiation: pleomorphic rhabdomyosarcoma (n=1), teratocarcinosarcoma-like with prominent rhabdomyoblasts (n=1), and adenocarcinoma-like with metaplastic bone (n=1). All cases were negative for S100, melanoma cocktail, HMB45, Melan A, and SOX10. Other markers showed following results: smooth muscle actin (1/14), p16 (1/14), TP53 (2/12), pancytokeratin (4/14), desmin (5/14), h-caldesmon (0/9), and MDM2/CDK4 (0/5). SMARCB1 was intact in 8/8 cases. Genotyping showed BRAF(V600E) mutation (5/14), NRAS mutation (5/14), and BRAF/NRAS wild-type (4/14). In conclusion, undifferentiated/dedifferentiated metastatic melanoma is likely underrecognized and frequently mistaken for undifferentiated sarcoma or other neoplasms. Diagnosis of undifferentiated sarcoma at sites where melanoma metastasis are frequent (eg, inguinal and axillary region) should be made with great caution and warrants exploration of the remote history. Genotyping is a helpful surrogate marker in classifying such difficult cases. In the light of available targeted therapies, recognition of undifferentiated/dedifferentiated metastatic melanoma is mandatory for appropriate treatment.

Epidermotropic metastatic melanoma clinically resembling agminated spitz nevi

Herein, we report a 36-year-old Asian male patient who presented with grouped multiple erythematous waxy papules and nodules on his right medial thigh. He had undergone amputation of the right second toe because of a stage IIa malignant melanoma, 3 years previously. At the time of surgery for the primary tumor, right inguinal lymph node dissection revealed no nodal involvement. Three years after the diagnosis of the primary tumor, crops of multiple erythematous papules and nodules developed. Initial histopathologic evaluation of the papules showed nests of small epithelioid cells similar to compound nevi. However, cytologic features, including high mitotic figures, lack of maturation, and some hyperchromatic nuclei suggested metastatic melanoma. In addition to the pathologic findings, the tumors were on the right thigh, which was the same side as the primary malignant melanoma. The patient underwent wide excision of the tumor and split-thickness skin grafting.

Dermoscopic patterns of melanoma metastases: interobserver consistency and accuracy for metastasis recognition

BACKGROUND

Cutaneous metastases of malignant melanoma (CMMM) can be confused with other skin lesions. Dermoscopy could be helpful in the differential diagnosis.

OBJECTIVES

To describe distinctive dermoscopic patterns that are reproducible and accurate in the identification of CMMM.

METHODS

A retrospective study of 146 dermoscopic images of CMMM from 42 patients attending a melanoma unit between 2002 and 2009 was performed. Firstly, two investigators established six dermoscopic patterns for CMMM. The correlation of 73 dermoscopic images with their distinctive patterns was assessed by four independent dermatologists to evaluate the reproducibility in the identification of the patterns. Finally, 163 dermoscopic images, including CMMM and nonmetastatic lesions, were evaluated by the same four dermatologists to calculate the accuracy of the patterns in the recognition of CMMM.

RESULTS

Five CMMM dermoscopic patterns had a good interobserver agreement (blue naevus-like, naevus-like, angioma-like, vascular and unspecific). When CMMM were classified according to these patterns, correlation between the investigators and the four dermatologists ranged from κ = 0.56 to κ = 0.7. In total, 71 CMMM, 16 angiomas, 22 blue naevi, 15 malignant melanomas, 11 seborrhoeic keratoses, 15 melanocytic naevi with a globular pattern and 13 pink lesions with a vascular pattern were evaluated according to the previously described CMMM dermoscopy patterns, showing an overall sensitivity of 67.9% (range 54.9-76%) and a specificity of 79.9% (range 68.5-93.5%) for the diagnosis of CMMM.

CONCLUSIONS

Five dermoscopic patterns of CMMM with good interobserver agreement obtained a high sensitivity and specificity in the diagnosis of metastasis, with the accuracy varying according to the experience of the observer.

Sinonasal blue naevus: case report and clinicopathological review

OBJECTIVE

To highlight the important clinical and histological features of sinonasal blue naevi.

METHODS

A case of blue naevus of the nasal cavity is described (including endoscopic and histological pictures) and the existing literature is reviewed.

RESULTS

There have been five reported cases (including the presented case). Clinically, sinonasal blue naevi are heavily pigmented lesions that are small and asymptomatic. Histopathologically, blue naevi exhibit heavily pigmented dendritic melanocytes that are never abnormal in form.

CONCLUSION

Blue naevus should be a differential diagnosis for pigmented lesions within the sinonasal cavity, despite its rarity. It may be initially suspected by its small size and asymptomatic nature. However, histological examination is required for definitive diagnosis, looking for the key microscopic features described above.

Sarcoma metastases to the skin: a clinicopathologic study of 65 patients

BACKGROUND

Sarcoma metastases to the skin are relatively rare, because most involve the lung, liver, or deep soft tissues. The authors of this report examined the distribution and clinical significance of cutaneous and superficial subcutaneous sarcoma metastases.

METHODS

Sixty-five patients with histologically confirmed dermal and superficial subcutaneous sarcoma metastases were identified in pathology files from more than 25,000 patients with sarcoma who were evaluated at The University of Texas M. D. Anderson Cancer Center from 1989 to 2009. Pathology slides and clinical and radiological information were evaluated.

RESULTS

Cutaneous metastases were documented histologically in <0.25% of patients. The mean patient age was 49 years (range, 16-79 years), and there was an equivalent ratio of men to women. The most common source of metastasis was leiomyosarcoma (28 of 65 patients; 43%). The most common region of first skin metastasis was head and neck (33 patients; 51%), and the scalp predominated (25 patients; 38%). The mean time from primary tumor diagnosis to skin metastasis was 48 months (range, 0-166 months). Fifty-three patients (81%) had multiple metastases (skin and other). Among the patients who had complete clinical information available, 31 patients (62%) had other metastases diagnosed before skin involvement, 17 patients (34%) had skin metastases diagnosed first, and 2 patients (4%) had simultaneous presentation. The following clinical outcomes were documented: Twenty-nine patients (45%) died of disease, 24 patients (37%) remained alive with disease, and 12 patients were lost to follow-up. The mean time to death was 80 months (range, 9-224 months) after primary diagnosis, 45 months (range, 5-94 months) after the first metastasis to any site, and 27 months (range, 5-65 months) after the first skin metastasis.

CONCLUSIONS

Sarcoma metastases to the skin are rare. In this large study, leiomyosarcoma was the most common source, and the scalp was the most frequent site. The majority of patient with skin metastases harbored metastases elsewhere. However, skin was the initial site of metastasis in approximately 1 in 3 patients. Thus, clinical correlation is needed before establishing a diagnosis of primary cutaneous sarcoma, particularly leiomyosarcoma of scalp. Finally, the current results indicated that skin metastasis usually is a late event in sarcoma clinical progression and heralds a poor prognosis.

Melanoma pathology: important issues for clinicians involved in the multidisciplinary care of melanoma patients

Histologic analysis remains the gold standard for diagnosis of melanoma. The pathology report should document those histologic features important for guiding patient management, including those characteristics on which the diagnosis was based and also prognostic factors. Pathologic examination of sentinel lymph nodes provides very important prognostic information. New techniques, such as comparative genomic hybridization and fluorescence in situ hybridization are currently being studied to determine their usefulness in the diagnosis of melanocytic lesions. Recent molecular studies have opened new avenues for the treatment of patients with metastatic melanoma (ie, targeted therapies) and molecular pathology is likely to play an important role in the emerging area of personalized melanoma therapy.

Cutaneous metastasis of hepatocellular carcinoma diagnosed by fine needle aspiration cytology and Hep Par 1 immunopositivity

Cutaneous metastasis of hepatocellular carcinoma (HCC) is very rare, accounting for less than 0.8% of all known cutaneous metastases and occurring in 2.7-3.4% of HCCs. With less than 50 such cases reported worldwide, most of which were diagnosed histologically on excised lesions, it can only be expected that diagnosis made on cytological features alone would be challenging. We report a case of cutaneous metastasis of HCC diagnosed based on cytological features and confirmed by Hep Par 1 immunopositivity of the cell block material. An 81-year-old man, who was known to have unresectable HCC, presented with a 1-month history of painless, left nasal alae mass. The mass measured 1.5 cm in diameter, and was multilobulated with a central necrosis. Fine needle aspiration of the mass was done. Smears were cellular, comprising of malignant cells in loose clusters and aggregates as well as singly dispersed. The malignant cells displayed moderate nuclear pleomorphism, occasional prominent nucleoli, and intranuclear pseudoinclusion. Cell block material demonstrated the trabeculae pattern of the malignant cells and Hep Par 1 immunopositivity. The final diagnosis of a metastatic cutaneous HCC was made. In conclusion, cutaneous HCC metastasis is rare and should be considered in the differential diagnosis in patients with a history of HCC presenting with suspicious skin lesion. In the right clinical setting, a confident diagnosis can be made in such cases by using the fine needle aspiration technique aided with immunopositivity for Hep Par 1 antibody of the aspirated material.

Re-inventing intratumoral immunotherapy for melanoma

Immunotherapeutics have been applied intratumorally to manage accessible lesions and to induce systemic immunity in malignant melanoma. Intratumoral bacillus Calmette-Guérin (BCG) has been used for 40 years, and intratumoral BCG, IL-2, IFN-α and imiquimod are recommended as treatment options for patients with in-transit melanoma metastases. Regression of cutaneous metastases can be achieved. Subcutaneous metastases are more refractory, and regression of uninjected, visceral metastases is infrequent. Other microbial products, cytokines, chemicals, immune cells, antibody and viral and plasmid vectors expressing immunologically active molecules have been tested. Antitumor activity has not been demonstrated to be superior to that of intratumoral BCG. There are few controlled trials, and whether survival is impacted with any approach has not yet been established. The immunotherapeutics applied and the intratumoral administration procedure itself can activate responses that are immune inhibitory. More rigorous clinical testing and improved understanding and modulation of regulatory immune responses are necessary.