Immunophenotypic heterogeneity of primary sinonasal melanoma with aberrant expression of neuroendocrine markers and calponin

Mimickers of neuroendocrine tumors on endoscopic ultrasound-guided fine-needle aspirate material: Need for caution

Cytologic diagnosis of neuroendocrine tumors can be straightforward on cytologic preparations, given the classical neuroendocrine morphology and expression of neuroendocrine markers confirmed by immunohistochemistry. However, overreliance on neuroendocrine markers can lead to misdiagnosis even if individual cell features suggest a neuroendocrine tumor. We present three unusual cases, two of which were initially diagnosed as neuroendocrine tumors and the third one carried preliminary diagnosis of neuroendocrine tumor on endoscopic ultrasound-guided fine-needle aspirates. These cases subsequently turned out to be cholangioblastic cholangiocarcinoma, metastatic melanoma, and gastric glomus tumor, respectively. We suggest approaches that could have pointed us towards the correct diagnosis at the outset and discuss potential pitfalls.

Neuroendocrine Transdifferentiation in Cutaneous Melanoma: A Case Report and Review of the Literature

ABSTRACT

Neuroendocrine transdifferentiation refers to the progressive transformation of a nonneuroendocrine tumor to the one showing evidence of neuroendocrine differentiation on morphological and immunohistochemical grounds. Although this phenomenon has been well-documented in certain malignancies, particularly prostatic adenocarcinoma after androgen deprivation, cases of neuroendocrine transdifferentiation in melanomas are exceptionally rare. Herein, we report a case of a conventional superficial spreading melanoma occurring on the skin of the leg in a young male which showed progressive neuroendocrine transdifferentiation as it progressed through 2 in-transit metastases and a nodal metastatic deposit over a 4-year period. The tumor retained the BRAF V600E mutation throughout the disease process, and disease control was achieved through dual BRAF inhibition therapy. The possibility of melanoma masquerading as a high-grade neuroendocrine malignancy when investigating tumors of unknown primary should be kept in the mind of clinicians and histopathologist alike as a potential diagnostic pitfall, thus helping avoid misdiagnosis and guide appropriate treatment strategies.

Top 10 Basaloid Neoplasms of the Sinonasal Tract

BACKGROUND

Basaloid neoplasms of the sinonasal tract represent a significant group of tumors with histological overlap but often with different etiologies (i.e., viral, genetics), clinical management, and prognostic significance.

METHODS

Review.

RESULTS

"Basaloid" generally refers to cells with coarse chromatin in round nuclei and sparse cytoplasm, resembling cells of epithelial basal layers or imparting an "immature" appearance. Tumors with this characteristic in the sinonasal tract are represented by a spectrum of benign to high-grade malignant neoplasms, such as adenoid cystic carcinoma, NUT carcinoma, sinonasal undifferentiated carcinoma, SWI/SNF complex-deficient carcinomas, and adamantinoma-like Ewing sarcoma.

CONCLUSION

In some instances, histology alone may be sufficient for diagnosis. However, limited biopsy material or fine-needle aspiration specimens may be particularly challenging. Therefore, often other diagnostic procedures, including a combination of histology, immunohistochemistry (IHC), DNA and RNA testing, and molecular genetics are necessary to establish an accurate diagnosis.

Desmoplastic Small Round Cell Tumor of the Head and Neck: A Potential Diagnostic Pitfall

Primary desmoplastic small round cell tumor (DSRCT) in the head and neck region is extremely rare. There is limited information about its clinicopathological characteristics, prognosis, and treatment modalities. The purpose of this study is to provide a comprehensive review of DSRCT occurring primarily in the head and neck, to demonstrate its peculiar morphology and immunohistochemical expression, and to address the differential diagnoses. A total of 25 cases were collected after a thorough review of the relevant literature. DSRCT was most frequently reported in the major salivary glands, followed by the eyes. Furthermore, some cases were misinterpreted as poorly differentiated carcinoma, Ewing sarcoma, and olfactory neuroblastoma. Diagnosing DSRCTs in the head and neck can be very challenging due to their rarity in this location, overlapping morphology, and immunohistochemistry. In these cases, following a systemic approach helps to solve diagnostic problems.

Sinonasal Mucosal Melanoma: An Update and Review of the Literature

ABSTRACT

Primary sinonasal mucosal melanoma (SNMM) is an aggressive tumor with high metastatic potential and poor outcomes. Presenting symptoms are nonspecific, and the nasal cavity is the most common site of origin followed by the maxillary and ethmoid sinuses. Histopathologically, SNMMs are pleomorphic and predominantly composed of epithelioid cell type. Identifying these tumors requires a high index of suspicion for melanoma and the use of a panel of immunohistochemical markers when typical histopathological features are missing. Not infrequently, these tumors are undifferentiated and/or amelanotic. Currently, SNMM falls into 2 different staging systems proposed by the American Joint Committee on Cancer, one for carcinoma of the nasal cavity and sinuses and the other for head and neck melanoma. Although therapeutic standards do not exist, surgical resection with adjuvant radiotherapy and/or systemic therapy may offer the best outcome. Lymphadenectomy including possible parotidectomy and neck dissection should be considered in patients with regional lymph node metastasis. However, the role of elective lymph node dissection is controversial. Genetic profiling has identified a number of recurrent gene mutations that may prove useful in providing targets for novel, emerging biological treatments. In this article, we provide an update on clinicopathological features, staging, molecular discoveries, and treatment options for SNMM.

Base of tongue metastasis of cutaneous malignant melanoma with rhabdoid and neuroendocrine features: Report of a rare case and review of the literature

Metastatic malignant melanoma (MM) represents a highly aggressive cancer associated with overall poor prognosis. Various anatomic sites can be affected, including the oral cavity and the oropharynx. It may mimic other entities by assuming a variety of clinical appearances and exhibiting a plethora of microscopic variations. Herein, we present a case of a 63-year-old male with a MM metastasizing to the base of tongue, which developed 5 years after the original diagnosis and treatment of cutaneous MM of the chest and heralded its relapse; subsequently, neurological symptoms developed as a result of metastasis to the brain. Diagnostic challenges were encountered, as the tongue lesion clinically masqueraded as a pedunculated reactive lesion and microscopically displayed unusual rhabdoid and neuroendocrine features. Tumor cells expressed S-100, HMB-45, Melan-A, and SOX-10, while most cells with rhabdoid morphology were also positive for myogenin and Myo-D1. Chromogranin and synaptophysin positivity was further noticed in a subset of cells, suggestive of focal neuroendocrine differentiation. Molecular investigation revealed mutations for the BRAF V600E gene. Divergent differentiation of tumor cells may cause diagnostic pitfalls necessitating thorough immunohistochemical analysis. The presence of rhabdoid features and neuroendocrine differentiation are very uncommon, while their co-existence is extremely rare. Better characterization of such microscopic variations in MMs with evaluation of their potential biologic significance is warranted.

Malignant Melanoma With Neuroendocrine Differentiation: A Case Report and Literature Review

Background

Melanoma has a wide range of histologic variants and cytomorphologic features that make its diagnosis challenging. Melanoma can also rarely have neuroendocrine markers adding further diagnostic uncertainty particularly given that unrelated tumor types, such as prostate cancer, can also display focal neuroendocrine differentiations.

Case presentation

Our patient is a 74-year-old Caucasian man found to have a lung mass. Initial biopsy revealed typical microscopic morphology and neuroendocrine differentiation consistent with small cell carcinoma. Despite standard chemoradiation treatment, the patient continued to progress with new metastasis in the brain, liver and bone. Subsequent chest wall biopsy revealed golden-brown pigment associated with melanin. Further tumor immunohistochemistry revealed extensive neuroendocrine differentiation with CD56, synaptophysin, and INSM1, as well as strong immunoreactivity for melanocyte markers including SOX10, S100, PRAME, and MITF, consistent with metastatic melanoma with neuroendocrine differentiation. Genomic testing revealed increased tumor mutational burden and alterations in NF1, BRAF, CDKN2A/B, TERT. The patient was transitioned to checkpoint inhibitor therapy with nivolumab and ipilimumab and had resolution of his intracranial mass and decrease in size of other metastatic lesions.

Conclusion

Often the combination of anatomic findings such as a lung mass, typical microscopic morphology, and confirmation of neuroendocrine differentiation correctly identifies a patient with small cell carcinoma. However, in a patient who fails to respond to treatment, a broader immunohistochemical workup along with molecular testing with additional tissue may be warranted.

Prognostic significance of the aberrant expression of neuroendocrine markers in melanomas

Background

Melanoma is a highly malignant tumor with diverse histopathological morphology and frequent aberrant expression of immunohistochemical markers. An occasionally reported phenomenon is the abnormal expression of neuroendocrine markers. Awareness of this situation is essential because such tumors need to be differentiated from neuroendocrine tumors because of their significant therapeutic and prognostic implications.

Methods

We retrospectively analyzed the expression of chromogranin A (CgA), synaptophysin (Syn) and CD56 as neuroendocrine markers in 308 cases with melanomas. Kaplan-Meier curves and Cox regression analyses were used for overall survival (OS) and progression-free survival (PFS) evaluation and comparison between neuroendocrine markers expression status in all melanoma cases or stage I–II cases.

Results

The expression of neuroendocrine markers in melanomas is not uncommon. CgA was positive in 6/304 (2.0%) cases, Syn in 26/304 (8.6%), and CD56 in 56/189 (29.6%). None of the cases co-expressed all the three markers. Focal or weak expression of at least one neuroendocrine marker was identified in 70/188 (37.2%) cases. The expression of CgA was correlated with age (p = 0.019), while the positive expression of Syn and CD56 showed borderline significance (p = 0.078 and 0.083, respectively), but not for any neuroendocrine marker expression. The expression of any neuroendocrine marker showed borderline significance with staging (p = 0.066). The expression of CgA, Syn, CD56, or any neuroendocrine marker did not correlate with clinicopathological features including sex, specimen type, origin, location, and histology subtype. Survival analyses revealed that the expression of neuroendocrine markers was not associated with OS or PFS.

Conclusions

Our study confirms that neuroendocrine marker expression is a common phenomenon in melanomas, but it has no prognostic significance. Nevertheless, awareness can avoid misdiagnosis in cases of melanomas with unusual morphology and immunophenotypes.

Aberrant Expression of Immunohistochemical Markers in Malignant Melanoma: A Review

Immunohistochemical stains are increasingly used to aid in the diagnosis of malignant melanoma, especially when the differentiation of the tumor is unclear based on examination with hematoxylin and eosin. However, aberrant expression of non-melanocytic markers has been reported in melanomas, which can sometimes be further complicated by the loss of conventional melanocytic markers. This review aims to summarize available data regarding unusual staining patterns in primary and metastatic malignant melanoma. It also raises awareness of the potential pitfalls and highlights the importance of appropriate use and interpretation of broad immunohistochemical markers in the context of clinical and histopathologic findings to facilitate the diagnosis of atypical cases of malignant melanoma.

Observed progression from melanosis with melanocyte hyperplasia to sinonasal melanoma with distant metastasis and a unique genetic rearrangement

Melanosis, clinically presenting as a benign macular hyperpigmentation, consists of increased pigmentation (melanotic or melanocytic) either in the mucosal epithelial cells or as subepithelial pigment-laden macrophages. On the other hand, primary sinonasal mucosal melanoma (SNMM) is a rare disease with poor prognosis and high rates of local recurrence and metastasis. We report follow-up on a previously presented case of a 53-year-old man with recurrent clinical melanosis that progressed from histopathological melanocytic hyperplasia to melanoma in situ over a period of 4.8 years (Yao et al. Allergy Rhinol (Providence), 2016;7(3):164-167). The patient experienced multiple recurrences and local spread despite multiple extensive surgeries. We now report that this patient ultimately developed bilateral invasive SNMM and died with metastatic melanoma. Molecular analysis of the invasive melanoma revealed ALK rearrangement, specifically an EML4-ALK fusion, which represents the first report of this particular genetic variant in mucosal melanoma.

Application of INSM1 in Diagnosis and Grading of Laryngeal Neuroendocrine Carcinoma

OBJECTIVE

Chromogranin (CHG), synaptophysin (Syn), and CD56 are generally used in a panel to support diagnoses of laryngeal neuroendocrine carcinomas (NECs). However, the absence of expression of these markers does not completely exclude the diagnosis. INSM1 is a novel marker that is considered sufficiently sensitive and specific for NE differentiation. The aim of this study is not only to detect its sensitivity and specificity, but also to evaluate its application in grading for laryngeal NECs.

METHODS

The clinicopathological characteristics of the 25 cases with laryngeal NECs were retrospectively analyzed. The expressions of INSM1, CHG, Syn, and CD56 were detected by immunohistochemistry.

RESULTS

Of the 25 laryngeal NECs, INSM1 had higher sensitivity (92%) than Syn (84%), CHG (76%) and CD56 (76%). The average H scores of INSM1, CD56, Syn, and CHG were 160, 37.5, 300, 300 for well-differentiated neuroendocrine carcinoma (WD-NEC); 190, 149, 209, 215 for moderately differentiated neuroendocrine carcinoma (MD-NEC); 251, 208, 104, 25 for poorly differentiated neuroendocrine carcinoma with small cell (SCNEC); 109, 160, 98, 26 for large cell types (LCNEC), respectively. Of these 98 non-neuroendocrine tumors, INSM1 expression was seen in nine (9%) tumors, all were squamous cell carcinoma. And INSM1 staining was generally focal.

CONCLUSION

INSM1 has high sensitivity and specificity in diagnosis of laryngeal NECs. For grading laryngeal NECs, Syn and CHG showed significant advantages in the diagnosis of WD-NEC and MD-NEC, whereas INSM1 and CD56 showed greater diagnostic value in the diagnosis of SCNEC and LCNEC, especially in SCNEC.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

Cutaneous melanoma dissemination is dependent on the malignant cell properties and factors of intercellular crosstalk in the cancer microenvironment (Review)

The incidence of cutaneous malignant melanoma has been steadily increasing worldwide for several decades. This phenomenon seems to follow the trend observed in many types of malignancies caused by multiple significant factors, including ageing. Despite the progress in cutaneous malignant melanoma therapeutic options, the curability of advanced disease after metastasis represents a serious challenge for further research. In this review, we summarise data on the microenvironment of cutaneous malignant melanoma with emphasis on intercellular signalling during the disease progression. Malignant melanocytes with features of neural crest stem cells interact with non‑malignant populations within this microenvironment. We focus on representative bioactive factors regulating this intercellular crosstalk. We describe the possible key factors and signalling cascades responsible for the high complexity of the melanoma microenvironment and its premetastatic niches. Furthermore, we present the concept of melanoma early becoming a systemic disease. This systemic effect is presented as a background for the new horizons in the therapy of cutaneous melanoma.

Sinonasal amelanotic melanoma with neuroendocrine differentiation: a diagnostic conundrum

Mucosal malignant melanoma of the head and neck (HN) is a rare and aggressive neoplasm which constitutes only 1% of all melanomas. Neuroendocrine differentiation is an extremely unusual phenomenon in mucosal melanomas, of which five cases have been reported. We report a rare case of a 63-year-old female who developed sinonasal amelanotic melanoma with immunohistochemical expression of neuroendocrine markers, presenting a diagnostic dilemma. Ultrastructural evidence of melanosomes and neurosecretory granules aided in arriving at the diagnosis. Aberrant immunoexpression of neuroendocrine markers, particularly in an amelanotic melanoma, has critical diagnostic implications, as various malignancies with undifferentiated histomorphology occur at this site, many of which stain positively with neuroendocrine markers. We discuss the differential diagnoses and recommend a high index of suspicion so as not to miss the diagnosis of mucosal melanoma at this location.

Diagnostic traps awaiting the head/neck pathologist: "Cytoplasm-poor" neoplasms

CONTEXT

Beyond squamous carcinoma, a variety of diagnostically challenging neoplasms arise within various head and neck sites. This is particularly the situation with neoplasms where little cellular cytoplasm is present to assist the pathologist in categorizing such lesions.

OBJECTIVE

To highlight diagnostic pitfalls that accompanying neoplasms composed primarily of 'cytoplasmically-poor' cells. These pitfalls include morphologic and immunohistochemical traps that emerge from this class of neoplasms.

DATA SOURCES

Selection of pathologic specimens from the author's personal files, and literature review.

CONCLUSIONS

Interpretative pitfalls regarding the histopathology and immunophenotype of small 'cytoplasmically-poor' neoplasms are a diagnostic hazard in head and neck surgical pathology practice, and require knowledge of histomorphologic plasticity and aberrant immunophenotyping.

INSM1 is a Sensitive and Specific Marker of Neuroendocrine Differentiation in Head and Neck Tumors

The head and neck is the site of a wide and sometimes bewildering array of neuroendocrine (NE) tumors. Although recognition of NE differentiation may be necessary for appropriate tumor classification and treatment, traditional NE markers such as synaptophysin, chromogranin, and CD56 are not always sufficiently sensitive or specific to make this distinction. Insulinoma-associated protein 1 (INSM1) is a novel transcription factor that has recently demonstrated excellent sensitivity and specificity for NE differentiation in various anatomic sites, but has not yet been extensively evaluated in tumors of the head and neck. We performed INSM1 immunohistochemistry on NE tumors (n=97) and non-NE tumors (n=626) across all histologic grades and anatomic subsites of the head and neck. INSM1 was positive in all types of head and neck NE tumors evaluated here (99.0% sensitivity), including middle ear adenoma, pituitary adenoma, paraganglioma, medullary thyroid carcinoma, olfactory neuroblastoma, small cell carcinoma, large cell NE carcinoma, and sinonasal teratocarcinosarcoma. Notably, it was positive in the vast majority of high-grade NE malignancies (95.8% sensitivity). INSM1 also was negative in almost all non-NE tumors (97.6% specificity) with the highest rates of reactivity in alveolar rhabdomyosarcoma and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily B, member 1 (SMARCB1)-deficient sinonasal carcinoma. These findings confirm that INSM1 may be used as a standalone first-line marker of NE differentiation for tumors of the head and neck.

Small round blue cell tumors of the sinonasal tract: a differential diagnosis approach

One of the most challenging diagnostic categories within tumors of the sinonasal tract is the small round blue cell tumors. Biopsies are usually small and limited, resulting in considerable diagnostic difficulty for practicing surgical pathologists. These tumors share several overlapping histologic and immunophenotypic findings while also showing considerable variation within and between cases. Specific tumor site of origin, imaging findings, and clinical findings must be combined with the histology and pertinent ancillary studies if the correct diagnosis is to be reached. Discrimination between neoplasms is critical as there are significant differences in therapy and overall outcome. It is important to have a well developed differential diagnosis for this category of tumors, where each of the diagnoses is considered, evaluated, and either confirmed or excluded from further consideration. In an undifferentiated tumor, showing a small round blue cell morphology, using the mnemonic 'MR SLEEP' helps to highlight tumors to consider: melanoma, mesenchymal chondrosarcoma, rhabdomyosarcoma, sinonasal undifferentiated carcinoma, squamous cell carcinoma (including NUT carcinoma), small cell osteosarcoma, lymphoma, esthesioneuroblastoma (olfactory neuroblastoma), Ewing sarcoma/primitive neuroectodermal tumor, pituitary adenoma, and plasmacytoma. A panel of pertinent immunohistochemistry studies, histochemistries and/or molecular tests should aid in reaching a diagnosis, especially when taking the pattern and intensity of reactions into consideration.

Sinonasal Small Round Blue Cell Tumors: An Immunohistochemical Approach

Although clinical history and morphologic appearance should be the initial considerations when evaluating small round blue cell tumors of the sinonasal tract, the final diagnosis often hinges on immunohistochemical findings. Unfortunately, interpretation of stains in these tumors is fraught with numerous pitfalls and limitations. This article presents an approach to sinonasal small round blue cell tumors based on four common immunohistochemical patterns: cytokeratin positivity, squamous marker positivity, neuroendocrine marker positivity, and cytokeratin negativity.

Pulmonary melanoma and "crazy paving" patterns in chest images: a case report and literature review

Background

In the lung, melanoma is mostly arranged as patterns of multiple nodules, solitary nodules, or miliary invasions. Very rarely, it also displays a “crazy paving” pattern (also described as a “paving stone,” “flagstone,” or “slabstone” pattern), which is rarer still in discrete bilateral nodules. This pattern is considered to be caused by pulmonary alveolar proteinosis, but its association with various diseases is unclear.

Case presentation

A 60-year-old man was diagnosed with pulmonary melanoma. Computed tomography revealed discrete bilateral nodules surrounded by a “paving” pattern. A literature review found more than 40 types of diseases that have presented with “paving” patterns in the lung—predominantly pulmonary alveolar proteinosis, viral pneumonia, exogenous lipoid pneumonia, bacterial pneumonia, pulmonary alveolar microlithiasis, interstitial pneumonia, ARDS, squalene aspiration pneumonia, radiation pneumonitis, drug-induced pneumonitis, pulmonary leptospirosis, pulmonary hemorrhage, and pulmonary nocardiosis.

Conclusions

We describe the first case of pulmonary melanoma in the form of discrete bilateral nodules accompanied with a computed tomography paving pattern. Although pulmonary paving patterns are rare, more than 40 diseases reportedly display them; clinicians should consider melanoma of the lung in differential diagnoses for patients who show such a pattern.

Aberrant intermediate filament and synaptophysin expression is a frequent event in malignant melanoma: an immunohistochemical study of 73 cases

Malignant melanomas are known to express vimentin, among other intermediate filaments. Though anomalous keratin expression by malignant melanoma has been reported, its frequency is not well-established and this phenomenon is not well-known. We have seen in consultation a number of malignant melanomas with anomalous expression of keratin, other intermediate filaments, or synaptophysin, and therefore studied a large group of primary and metastatic melanomas to determine the frequency of these events. About 73 cases of malignant melanoma (22 primaries and 51 metastases) from 71 patients (51 male, 20 female; mean 59 years, range 17-87 years) were retrieved from our archives. Prior diagnoses were confirmed by re-review of hematoxylin and eosin sections and relevant (e.g., S100 protein, HMB45, Melan-A, and tyrosinase) immunohistochemical studies. Available sections were immunostained for keratin (OSCAR and AE1/AE3 antibodies), desmin, neurofilament protein, glial fibrillary acidic protein, synaptophysin, and chromogranin A. Not all cases could be tested for all markers. Cases were predominantly epithelioid (48/73, 66%) or spindle cell/desmoplastic (25/73, 34%). S100 protein, Melan-A, HMB45, and tyrosinase were positive in 60/65 (92%), 34/64 (53%), 30/60 (50%), 25/48 (52%) of cases, respectively. All five S100-protein-negative cases expressed at least one of the other melanocytic markers: Melan-A (two of four, 50%), HMB45 (two of three, 67%), and tyrosinase (one of two, 50%). All cases expressed at least one melanocytic marker. Cases were positive for keratin (OSCAR, 17/61, 28%; AE1/AE3, 16/40, 40%), desmin (11/47, 24%), neurofilament protein (5/31, 16%), glial fibrillary acidic protein (3/32, 9%), and synaptophysin (10/34, 29%), typically only in a minority of cells. Chromogranin was negative (0/32, 0%). Altogether 9/73 cases (12%) showed expression of >1 intermediate filament. All S100-protein-negative melanomas showed anomalous intermediate filament expression (keratin--one case, desmin--three cases, neurofilament protein--one case). Anomalous intermediate filament or synaptophysin expression was more common in epithelioid (intermediate filament, 27/48, 56%; synaptophysin, 7/22, 32%) as compared with spindle cell/desmoplastic (intermediate filament, 8/25, 32%; synaptophysin, 3/12, 25%) melanomas. Overall, 48% (35/73) of cases showed anomalous expression of at least one intermediate filament. Anomalous expression of all intermediate filaments and synaptophysin was found in significant subsets of malignant melanoma, representing potentially serious diagnostic pitfalls. While the inclusion of consultation cases may inflate the frequency of these findings in this series, similar findings were also seen in institutional cases. Malignant melanoma showing anomalous intermediate filament and synaptophysin expression may easily be mistaken for carcinomas, rhabdomyosarcomas, and neuroendocrine tumors. Awareness of this phenomenon, careful histopathological evaluation, and an appropriate melanocytic immunohistochemical panel should facilitate the diagnosis of malignant melanoma with unusual immunophenotypes.

Primary mucosal melanoma of the sinonasal tract: a clinicopathologic and immunohistochemical study of thirty-two cases

Sinonasal mucosal melanoma is a rare disease with poor survival. These tumors may have associated intraepithelial melanocytic proliferations, which are not extensively characterized. This retrospective analysis of 32 patients with sinonasal mucosal melanoma examined associated intraepithelial melanocytic proliferations in the context of diagnostic and prognostic features. Patient age ranged from 30 to 90 years (median 71) with a male to female ratio of approximately 3:2. Follow up for 31 patients ranged from 5 to 211 months (mean 42 months). Most patients died from melanoma-associated causes (18/31, 58 %), six (19 %) died from unknown causes, two (6 %) were alive with metastatic disease, and only five patients (16 %) remained alive without melanoma. The tumors were histopathologically heterogeneous, displaying epithelioid, spindled, and small cell cytomorphology. The presence of >2 mitoses/mm(2) and necrosis correlated with tumor progression and overall survival, respectively (p = 0.04 for both). Melanoma in situ, defined as a confluent intraepithelial proliferation of cytologically atypical melanocytes, was identified in 20 of 30 evaluable cases (67 %) and confirmed with immunohistochemical staining for microphthalmia-associated transcription factor. Melanocytic hyperplasia, defined as intraepithelial melanocytic proliferation without confluent growth or marked atypia, was seen in five cases (16 %). This incidence of associated intraepithelial melanocytic proliferations (83 %) is higher than previously reported. Because of the locally aggressive nature of these tumors, an awareness of the high rate of associated intraepithelial melanocytic proliferations may inform future studies of therapeutic options.

Metastatic melanoma mimicking solitary fibrous tumor: report of two cases

Malignant melanomas are known for their remarkable morphological variation and aberrant immunophenotype with loss of lineage-specific markers, especially in recurrences and metastases. Hot spot mutations in BRAF, NRAS, GNAQ, and GNA11 and mutations in KIT are oncogenic events in melanomas. Therefore, genotyping can be a useful ancillary diagnostic tool. We present one case each of recurrent and metastatic melanoma, both showing histological and immunohistochemical features of solitary fibrous tumor (SFT). Mutational analysis detected BRAF and NRAS mutations in the primary and secondary lesions, respectively. This result confirmed the diagnosis of recurrent/metastastic melanoma.

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.

Current diagnostic strategies for undifferentiated tumours of the nasal cavities and paranasal sinuses

Several malignant tumours occurring in the sinonasal tract may present with an undifferentiated morphology. Overall, these lesions pose significant diagnostic difficulties for the surgical pathologist, especially in limited biopsy material, but their correct classification is becoming increasingly important for an appropriate treatment strategy. This review deals with the criteria for differential diagnosis of these neoplasms, with emphasis on recent advances in immunohistochemistry and molecular biology, as well as with previous progress in electron microscopy. Through careful microscopic examination of haematoxylin and eosin-stained sections, in the light of clinical information and imaging data, a list of differential diagnoses can be made and an appropriate panel of antibodies can be chosen to further categorize the tumour. An initial panel including cytokeratins, synaptophysin, S100 protein, desmin and CD45 may allow the classification of most lesions or may help to narrow the list of differential diagnoses. Further refinement can be obtained through second-line markers, including in-situ hybridization for Epstein-Barr virus, other neuroendocrine markers, melanocytic markers, myogenin, CD99, other lymphocyte markers, and CD138 and light chains. Finally, molecular analysis can further assist in the recognition of specific entities such as nuclear protein in testis midline carcinoma, Ewing's sarcoma/peripheral neuroectodermal tumour, alveolar rhadbomyosarcoma, and poorly differentiated synovial sarcoma.