Merkel Cell Carcinoma: An Immunotherapy Fairy-Tale?

Merkel cell carcinoma (MCC) is a rare, highly aggressive, neuroendocrine cutaneous tumor. The incidence of MCC is growing worldwide, and the disease-related mortality is about three-fold higher than melanoma. Since a few years ago, very little has been known about this disease, and chemotherapy has been the standard of care. Nowadays, new discoveries about the pathophysiology of this neoplasm and the introduction of immunotherapy allowed to completely rewrite the history of these patients. In this review, we provide a summary of the most important changes in the management of Merkel cell carcinoma, with a focus on immunotherapy and a landscape of future treatment strategies.

Digital Papillary Adenocarcinoma: Case of a Rare Malignant Cutaneous Tumor of the Eccrine Sweat Gland

Digital papillary adenocarcinoma (DPA) is a rare cutaneous tumor originating from the eccrine sweat glands. These lesions occur almost exclusively on the digits of the hands and feet, where there is a high concentration of eccrine glands. The diagnosis is made histologically, and the course of the malignancy tends to be very aggressive with high rates of recurrence and early metastasis at the time of diagnosis. Due to the low incidence of these lesions, there have been minimal objective data from clinical studies to recommend specific treatment strategies. Wide local excision versus digital amputation proximal to the lesion has been debated for primary treatment, while there are no data to support routine implementation of adjuvant chemotherapy or radiation, despite its metastatic nature. This article presents a case of long-standing, previously undiagnosed DPA. The lesion appeared more inconspicuous on gross examination than other reports in the literature, and diagnosis was made with punch biopsy and confirmed postsurgically. To date, the patient has not had recurrence, although she is being monitored for potential metastatic deposits in her lungs. Clinical dermatologists should be aware of the high mortality burden this lesion may inflict if left undiagnosed or mistreated.

The Management of Skin Defects at the Extremities Secondary to Malignant Cutaneous Tumor Resection by Split-Thickness Skin Grafts

We report in the light of a literature review the results of 20 patients treated by split-thickness skin grafts (STSG) at the extremities to cover skin defects secondary to malignant cutaneous tumor resection between 2012 and 2016 with a view to a prospective study with longer following up and a greater number of patients.

Eccrine Porocarcinoma: A Challenging Diagnostic and Therapeutic Tumoral Entity

Eccrine porocarcinoma is a rare malignant cutaneous tumor with high rates of extracutaneous spread, and its diagnosis and management can be quite challenging. This is a case of an 82-year-old woman presenting with an asymptomatic and chronic pubic skin lesion for whom the work-up required many investigations and procedures to confirm the diagnosis of metastatic eccrine porocarcinoma. Indeed, the patient underwent a wide local excision of the skin lesion, imaging with an FDG-PET scan, a colonoscopy, and two inguinal node dissections. As illustrated in this case, surgery should always be considered to achieve disease remission. Other treatments such as chemotherapy and radiotherapy have also been reported in the literature without clear standard guidelines.

Primary gastric melanoma of unknown origin: a case report and short literature review

Though being usually a cutaneous tumor, melanomas can occur in several extracutaneous sites. Primary mucosal melanomas are rare, and primary gastric mucosal melanomas are considered extremely rare. Compared with cutaneous and ocular melanoma, mucosal melanomas have the lowest five-year survival. High level of suspicion of such rare condition may be the only way for early detection, diagnosis and chance for successful management of similar cases. In the present report, a case of a primary gastric melanoma in a 73-year-old man is described, along with a short review of the literature

Merkel Cell Carcinoma of Unknown Primary: Immunohistochemical and Molecular Analyses Reveal Distinct UV-Signature/MCPyV-Negative and High Immunogenicity/MCPyV-Positive Profiles

Background: Merkel cell carcinomas of unknown primary (MCC-UPs) are defined as deep-seated tumors without an associated cutaneous tumor. Although the distinction has important clinical implications, it remains unclear whether these tumors represent primary tumors of lymph nodes or metastatic cutaneous primaries. Methods: We compared the immunohistochemical profiles of four groups of MCCs (Merkel cell polyomavirus (MCPyV)-positive UP, MCPyV-negative UP, MCPyV-positive known primary (KP), and MCPyV-negative KP) using B-cell and pre-B-cell markers, cell cycle regulating proteins, follicular stem cell markers, and immune markers, and performed next generation and Sanger sequencing. Results: Virus-positive and virus-negative MCC-UPs exhibited an immunoprofile similar to virus-positive and virus-negative primary cutaneous MCCs, respectively. MCC-UP tumors (both virus-positive and -negative) were immunogenic with similar or even higher tumoral PD-L1 expression and intratumoral CD8 and FoxP3 infiltrates in comparison to MCPyV-positive cutaneous tumors. In addition, similar to primary cutaneous MCCs, MCPyV-negative MCC-UPs exhibited UV signatures and frequent high tumor mutational burdens, whereas few molecular alterations were noted in MCPyV-positive MCC-UPs. Conclusions: Our results showed distinct UV-signatures in MCPyV-negative tumors and high immunogenicity in MCPyV-positive tumors. Although additional studies are warranted for the MCPyV-positive cases, our findings are supportive of a cutaneous metastatic origin for MCPyV-negative MCC-UP tumors.

Vladimír Bartoš

Desmoplastic Spitz nevus (DSN) is an uncommon variant of melanocytic nevus rarely encountered in dermatological practice. Herein, we describe a 54-year-old male who presented himself with a cutaneous tumor arising from the left arm. Histology revealed an intradermal proliferation of somewhat pleomorphic, epithelioid, spindled melanocytes in a background of desmoplastic stroma. A perineural invasion of tumor cells was found. Proliferative and mitotic rates were minimal. The tumor was diffusely positive for S-100 protein, PNL-2, and SOX-10, and only occasionally reactive for melan-A and HMB-45. The final diagnosis of DSN was established. Although DSN is a completely benign tumor, it may result in diagnostic pitfalls. Due to its unusual histopathological features, it may be confused with a malignant desmoplastic melanoma. A knowledge of the clinicopathological differences between the two prognostically distinct skin tumor entities is essential for a differential diagnosis.