Tumoral melanosis mimicking residual melanoma in the setting of talimogene laherparepvec treatment.

Talimogene laherparepvec (T-VEC) has become an increasingly popular treatment option for surgically non-resectable, recurrent melanoma, usually of cutaneous metastases. The complete response (CR) rate has been reported to be ~20% with a median of ~9 months to achieve it. In real-world practice, decrease of tumor size often occurs rapidly within the first 2-3 months, while improvement of the pigmentation takes several more months. Such clinical observation of lasting pigmentation could be explained by tumorous melanosis-a histopathological term referring to the presence of a melanophage-rich inflammatory infiltrate without remaining viable tumor cells. Herein, we report six patients with metastatic cutaneous melanoma who were treated with T-VEC. Biopsies were performed after observing clinical responses in the injected tumors. Pathological evaluation demonstrated non-viable or absent tumor tissue with tumorous melanosis in all cases. To accurately assess response to therapy and potentially decrease unnecessary additional T-VEC treatments, serial biopsy of 'stable' lesions should be considered to assess the presence or absence of viable tumor.

How we treat Merkel cell carcinoma: within and beyond current guidelines.

Merkel cell carcinoma (MCC) is an aggressive skin cancer associated with a high risk of local recurrence and distant metastasis. Optimal care of this potentially life-threatening cancer is critical but challenging because: physicians are often unfamiliar with its management due to rarity, and MCC management remains controversial, in part because it is rapidly evolving across multiple specialties. While guidelines offer a broad overview of management, they are often not sufficient when making decisions for individual patients. Herein, we present a literature review as well as practical approaches adopted at our institutions for staging, surveillance and therapy of MCC. Each of these areas are discussed in light of how they can be appropriately customized for prevalent but challenging situations. We also provide representative examples of MCC patient scenarios and how they were managed by a multidisciplinary team to identify suitable evidence-based, individualized treatment plans.

Lay abstract Merkel cell carcinoma (MCC) is a skin cancer with a high risk of recurrence and distant spread. Optimal care of this cancer is important. However, management is challenging because it is rare and its treatment is continuously evolving across multiple specialties. While treatment guidelines offer a broad overview of management, they are often not detailed enough to provide appropriate patient-specific assistance. Herein, we present a review of recent studies and our suggestions relevant to MCC staging, surveillance and treatment options. Each of these areas are discussed in light of how they can be appropriately customized for challenging situations often encountered by practitioners. We also provide representative examples of MCC patient scenarios and how they were managed by a multidisciplinary team to identify evidence-based, individualized treatment plans.

Narrow excision margins are appropriate for Merkel cell carcinoma when combined with adjuvant radiation: Analysis of 188 cases of localized disease and proposed management algorithm.

BACKGROUND: Merkel cell carcinoma (MCC) management typically includes surgery with or without adjuvant radiation therapy (aRT). Major challenges include determining surgical margin size and whether aRT is indicated. OBJECTIVE: To assess the association of aRT, surgical margin size, and MCC local recurrence. METHODS: Analysis of 188 MCC cases presenting without clinical nodal involvement. RESULTS: aRT-treated patients tended to have higher-risk tumors (larger diameter, positive microscopic margins, immunosuppression) yet had fewer local recurrences (LRs) than patients treated with surgery only (1% vs 15%; P = .001). For patients who underwent surgery alone, 7 of 35 (20%) treated with narrow margins (defined as ≤1.0 cm) developed LR, whereas 0 of 13 patients treated with surgical margins greater than 1.0 cm developed LR (P = .049). For aRT-treated patients, local control was excellent regardless of surgical margin size; only 1% experienced recurrence in each group (1 of 70 with narrow margins ≤1 cm and 1 of 70 with margins >1 cm; P = .56). LIMITATIONS: This was a retrospective study. CONCLUSIONS: Among patients treated with aRT, local control was superb even if significant risk factors were present and margins were narrow. We propose an algorithm for managing primary MCC that integrates risk factors and optimizes local control while minimizing morbidity.

Patterns of distant metastases in 215 Merkel cell carcinoma patients: Implications for prognosis and surveillance.

Approximately one-third of Merkel cell carcinoma (MCC) patients eventually develop distant metastatic disease. Little is known about whether the location of the primary lesion is predictive of initial distant metastatic site, or if survival likelihood differs depending on the metastatic site. Such data could inform imaging/surveillance practices and improve prognostic accuracy. Multivariate and competing-risk analyses were performed on a cohort of 215 MCC patients with distant metastases, 31% of whom had two or more initial sites of distant metastasis. At time of initial distant metastasis in the 215 patients, metastatic sites (n = 305) included non-regional lymph nodes (present in 41% of patients), skin/body wall (25%), liver (23%), bone (21%), pancreas (8%), lung (7%), and brain (5%). Among the 194 patients who presented with MCC limited to local or regional sites (stage I-III) but who ultimately developed distant metastases, distant progression occurred in 49% by 1 year and in 80% by 2 years following initial diagnosis. Primary MCC locations differed in how likely they were to metastasize to specific organs/sites (P < .001). For example, liver metastases were far more likely from a head/neck primary (43% of 58 patients) versus a lower limb primary (5% of 39 patients; P < .0001). Skin-only distant metastasis was associated with lower MCC-specific mortality as compared to metastases in multiple organs/sites (HR 2.7; P = .003), in the liver (HR 2.1; P = .05), or in distant lymph nodes (HR 2.0; P = .045). These data reflect outcomes before PD1-pathway inhibitor availability, which may positively impact survival. In conclusion, primary MCC location is associated with a pattern of distant spread, which may assist in optimizing surveillance. Because it is linked to survival, the site of initial distant metastasis should be considered when assessing prognosis.