Squamomelanocytic Tumor: A Case Report and Further Insights Into Its Possible Histogenesis

Squamomelanocytic Tumor, An Entity Still Shrouded in Mystery: Case Report and Literature Review

Cutaneous squamomelanocytic tumor (SMT) is a very rare cutaneous malignancy, composed of a dual phenotypic population of both malignant melanocytes and keratinocytes, intimately intermingled together. Herein, we report a new case of a SMT occurring in an 82-year-old man, located on the scalp. Histopathology revealed a mixed population consisting of squamous cell carcinoma and melanoma within the same lesion, also confirmed using immunohistochemical staining for high molecular-weight cytokeratins (HMWCKs) and Melan-A. Moreover, to the best of our knowledge, for the first time, we tested SMT for the preferentially expressed antigen in melanoma (PRAME), which revealed a strong and diffuse positivity in the melanocytic component. These tumors need to be distinguished by more frequent collision tumors and colonization. Furthermore, we provide a comprehensive review of the literature, focusing on clinical and histopathological aspects, biological behavior and still-debated, but fascinating histogenesis of this elusive entity.

A Combined Spindle Cell Melanoma and Sarcomatoid Squamous Cell Carcinoma: A Rather Unique Squamomelanocytic Tumor

ABSTRACT

Squamomelanocytic tumor is a poorly defined term that indicates co-occurrence of malignant melanoma and squamous cell carcinoma within the same lesion. We present an unusual case of squamomelanocytic tumor in which both intermingling components showed predominantly spindle cell morphology and were confirmed with double staining for SOX-10 and AE1/AE3.

Combined tumour of aberrant cytokeratin expressing acral lentiginous melanoma and poroma: Diagnostic challenge

Combined tumours are uncommon and therefore these tumours may pose a diagnostic challenge. In the current case report, it is aimed to present the clinicopathological features of a combined tumour including melanoma with aberrant cytokeratin expression and poroma.

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.

Uncommon Histopathological Variants of Malignant Melanoma: Part 1

Despite new horizons opened by recent advances in molecular pathology, histological evaluation still remains the diagnostic gold standard regarding cutaneous melanocytic neoplasms. Several histological variants of melanoma have been described, and their knowledge is crucial for accurate diagnosis and classification of cases with unusual clinicopathological features. Uncommon histological variants of melanoma have been described based on a broad constellation of features, including architectural pattern, stromal alterations, cytological attributes, and other morphological properties. This review is aimed at providing an extensive discussion of unusual but distinctive histopathological variants of melanoma.

Combined cutaneous tumors with a melanoma component: A clinical, histologic, and molecular study

BACKGROUND

The histogenesis and clinical behavior of combined cutaneous tumors (CCTs) in which the mesenchymal component consists of melanoma remain unclear.

OBJECTIVE

We sought to characterize the clinical, histologic, and molecular findings in CCTs with an epithelial and a melanoma component.

METHODS

We retrospectively reviewed the records from 2 institutions for CCTs. Fluorescence in situ hybridization was performed to assess chromosomal copy number alterations in both components.

RESULTS

Sixteen CCTs were included. The most common subtype was the squamomelanocytic tumor (11), followed by the basomelanocytic tumor (3) and the trichoblastomelanoma (2). CCTs were more common in men (87%), on the head and neck (57%), and had extensive solar elastosis (81%). The median follow-up was 25 months (range, 8-167 months). One case had an adverse outcome. Fluorescence in situ hybridization revealed chromosomal alterations in approximately 55% of the cases. Five cases showed chromosomal gains only in the melanocytic component. One case showed 11q13 gains in both the epithelial and melanocytic components.

LIMITATIONS

Our study is retrospective and the sample is small.

CONCLUSIONS

The low incidence of adverse outcomes suggests that CCT may be more indolent than noncombined tumors. 11q13 amplification in both components supports the theory of dual differentiation from a common progenitor cell.

Significance of circulating tumor cells in soft tissue sarcoma

Circulating tumor cells can be detected from the peripheral blood of cancer patients. Their prognostic value has been established in the last 10 years for metastatic colorectal, breast, and prostate cancer. On the contrary their presence in patients affected by sarcomas has been poorly investigated. The discovery of EpCAM mRNA expression in different sarcoma cell lines and in a small cohort of metastatic sarcoma patients supports further investigations on these rare tumors to deepen the importance of CTC isolation. Although it is not clear whether EpCAM expression might be originally present on tumor sarcoma cells or acquired during the mesenchymal-epithelial transition, the discovery of EpCAM on circulating sarcoma cells opens a new scenario in CTC detection in patients affected by a rare mesenchymal tumor.

Primary cutaneous carcinosarcoma: insights into its clonal origin and mutational pattern expression analysis through next-generation sequencing

Primary cutaneous carcinosarcoma is a rare biphenotypic neoplasm exhibiting both epithelial and sarcomatous elements. Even though its origin and biological aspects remain poorly understood, it has been postulated that this tumor may arise from progenitor cells, which subsequently differentiate into distinct tumor components. We have investigated the histological and immunohistochemical staining patterns of a cutaneous carcinosarcoma case, as well as its ultrastructural aspects. In addition, sarcomatous and epithelial tumor components were separated by laser capture microdissection and subjected to targeted, high-depth, next-generation sequencing of a 46-cancer gene panel to asses the gene mutational pattern amongst both components. There were transitional cells at the epithelial/mesenchymal transition that labeled with putative progenitor cell markers (K19, c-kit, CD34 and Bcl-2). There was shared reactivity to antibodies directed against the progenitor cell marker EpCAM (epithelial cell adhesion molecule) in both components. Ultrastructurally, individual cells were demonstrated to have overlapping features of epithelial and mesenchymal differentiation. The mutational analysis revealed point mutations in exon 5 of TP53, which were identical in both the epithelial and sarcomatous components, and which were concordant with p53 expression at a tissue level. The aforementioned histological, ultrastructural, immunohistochemical and mutational pattern is strongly suggestive of a common clonal origin to the distinct elements of this tumor.