Prognostic significance of the aberrant expression of neuroendocrine markers in melanomas

An assessment of "neuroendocrine differentiation" in malignant melanomas of the sinonasal and oral region

Mucosal melanomas often require a detailed differential diagnosis and immunochemical study due to their different morphology and pattern characteristics. The tumors may also show fibroblastic, schwannian, smooth muscle, rhabdomyosarcomatous, gangliocytic, epithelial, and neuroendocrine differentiation. All these features can lead to serious diagnostic difficulties. The study aimed to determine the frequency of neuroendocrine differentiation in melanomas of the sinonasal and oral regions and to assess whether there is any relationship between neuroendocrine differentiation and clinical, histopathological, and other immunophenotypic features of this neoplasm. The study included 18 cases diagnosed with oral or sinonasal malignant melanoma. Neuroendocrine differentiation was determined by immunohistochemistry using synaptophysin, chromogranin, CD56, and INSM-1. A cut-off defining neuroendocrine differentiation in malignant melanomas has not been established in the literature. Because of this, any degree of neuroendocrine marker expression was considered as indicative of "neuroendocrine differentiation" without setting any cut-off. Neuroendocrine differentiation was observed in 13 of 18 cases (72.2 %) when a single positive neuroendocrine marker was considered sufficient. The number of cases with at least two positive neuroendocrine markers was 8/18 (44.4 %). Synaptophysin, chromogranin A, CD56, and INSM1 were positive in 33.3 %, 13.3 %, 56.2 %, and 47.1 % of cases, respectively. The results of our study suggest that neuroendocrine differentiation is not uncommon in oral and sinonasal melanomas. Knowing that malignant melanomas can show neuroendocrine differentiation will prevent diagnostic pitfalls.

EGR3 Inhibits Tumor Progression by Inducing Schwann Cell-Like Differentiation

The mechanism and function of the expression of Schwann characteristics by nevus cells in the mature zone of the dermis are unknown. Early growth response 3 (EGR3) induces Schwann cell-like differentiation of melanoma cells by simulating the process of nevus maturation, which leads to a strong phenotypic transformation of the cells, including the formation of long protrusions and a decrease in cell motility, proliferation, and melanin production. Meanwhile, EGR3 regulates the levels of myelin protein zero (MPZ) and collagen type I alpha 1 chain (COL1A1) through SRY-box transcription factor 10 (SOX10)-dependent and independent mechanisms, by binding to non-strictly conserved motifs, respectively. Schwann cell-like differentiation demonstrates significant benefits in both in vivo and clinical studies. Finally, a CD86-P2A-EGR3 recombinant mRNA vaccine is developed which leads to tumor control through forced cell differentiation and enhanced immune infiltration. Together, these data support further development of the recombinant mRNA as a treatment for cancer.

Malignant Melanoma With Neural Marker-Positive Distant Organ Cancers

Malignant melanoma is a melanocyte-derived tumor known for its aggressive clinical behavior. Melanocytes originate from the neural crest, which also gives rise to neural tissues. Malignant melanoma can occasionally exhibit neural differentiation. We report a case of a 70-year-old male with malignant melanoma exhibiting neural marker positivity in the absence of typical melanoma markers. The patient initially presented with a dark nodule on his left heel, which was confirmed as malignant melanoma through cytology. Surgical resection and lymph node dissection were performed, revealing atypical melanocytes. Despite postoperative nivolumab treatment, metastases in the brain and lungs were observed. Histological examination of the brain tumor showed neural differentiation markers (thyroid transcription factor 1 (TTF-1), cytokeratin 7 (CK7), AE1/AE3, and epidermal growth factor receptor (EGFR)) with negative melanoma markers. The patient eventually succumbed to the disease despite multiple treatments. An autopsy revealed multiple organ tumors (brain, duodenum, stomach, liver, and bile duct) negative for melanoma markers but positive for neuroendocrine markers (CD56, synaptophysin, and chromogranin A). This case suggests two possibilities: the coexistence of malignant melanoma with neuroendocrine tumors or a transformation of melanoma into a neuroendocrine phenotype. This case highlights the need for clinicians to consider the potential for melanoma to lose typical markers and transform into neuroendocrine cancer.

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 Histological Mimics of Neuroendocrine Carcinoma You Should Not Miss in the Head and Neck

BACKGROUND

The spectrum of neuroendocrine neoplasia (NEN) of the head and neck region is wide-ranging and diverse, including a variety of diagnoses stretching from benign and low-malignant tumor forms to highly proliferative, poor prognosis neuroendocrine carcinoma (NEC). Moreover, there are several non-neuroendocrine differential diagnoses to keep in mind as well, displaying various degree of morphological and/or immunohistochemical overlap with bona fide neuroendocrine lesions.

METHODS

Review.

RESULTS

While the growth patterns may vary, well-differentiated NEN usually display a stippled "salt and pepper" chromatin, a granular cytoplasm, and unequivocal expression of neuroendocrine markers such as chromogranin A and synaptophysin. However, these features are often less pronounced in NEC, which may cause diagnostic confusion-not the least since several non-NEC head and neck tumors may exhibit morphological similarities and focal neuroendocrine differentiation.

CONCLUSION

As patients with NEC may require specific adjuvant treatment and follow-up, knowledge regarding differential diagnoses and potential pitfalls is therefore clinically relevant. In this review, the top ten morphological and/or immunohistochemical mimics of NEC are detailed in terms of histology, immunohistochemistry, and molecular genetics.

Primary neuroendocrine tumors and primary neuroendocrine carcinomas of the liver: a proposal for a multidiscipline definition

Primary hepatic neuroendocrine tumors and primary hepatic neuroendocrine carcinomas are rare and pose challenges for both diagnosis and for determining whether the tumor is primary to the liver versus metastatic disease. The lack of a uniform definition for primary hepatic neuroendocrine neoplasms is also a limitation to understanding and treating these rare tumors. Recently, there have been significant histological advances in the diagnosis and classification of neuroendocrine tumors in general, as well as significant advances in imaging for neuroendocrine neoplasms, all of which are important for their treatment. This article presents a multiple disciplinary definition and proposed guidelines for diagnosing a neuroendocrine tumor/neuroendocrine carcinomas as being primary to the liver.

Aberrant synaptophysin expression in classic Hodgkin lymphoma

Background

Synaptophysin is an immunohistochemical marker for neuroendocrine differentiation and is widely used in pathologic diagnosis. Its expression in malignant lymphoma has not yet been described. However, we experienced an index case of classic Hodgkin lymphoma with synaptophysin expression. This experience prompted us to investigate synaptophysin expression in classic Hodgkin lymphoma.

Method

Immunohistochemical staining of synaptophysin was performed in 59 diagnosed cases of classic Hodgkin lymphoma, 10 anaplastic large cell lymphomas, 16 diffuse large B-cell lymphomas, and 5 extranodal marginal zone lymphoma of the mucosa-associated tissue. Synaptophysin-positive cases were stained for both chromogranin and CD56a.

Result

Of 59 classic Hodgkin lymphoma cases, 11 (19%) were positive for synaptophysin. None of the anaplastic large cell lymphomas expressed synaptophysin. Synaptophysin showed weak but specific expression in the cytoplasm of the Hodgkin lymphoma tumor cells. Other background inflammatory cells (such as macrophages, B-, and T-lymphocytes) were all negative for synaptophysin expression. Chromogranin and CD56a were not expressed in the synaptophysin-positive classic Hodgkin lymphomas.

Conclusions

Synaptophysin is an integral glycoprotein present in presynaptic vesicles of neurons and neuroendocrine cells. It is a diagnostic marker for neuroendocrine tumors. Aberrant synaptophysin expression has been reported in non-neuroendocrine tumors but not in lymphoma or leukemia. To the best of our knowledge, synaptophysin positivity has only been reported in a single case of precursor T-lymphoblastic leukemia/lymphoma to date. Our study showed that aberrant synaptophysin expression in classic Hodgkin lymphoma is an unexpectedly frequent finding. The mechanism underlying, and prognostic significance of, such aberrant expression is unclear. Thus, in a small biopsy, aberrant synaptophysin expression could be a diagnostic pitfall and should be carefully avoided.

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.