Sentinel lymph node biopsy in desmoplastic melanoma - the percent desmoplastic component matters: A systematic review

An Evaluation of Sentinel Lymph Node Biopsy Guideline Adherence in Melanoma

BACKGROUND

Regional lymph nodes are a common first site of metastasis in patients diagnosed with invasive melanoma. Knowledge of sentinel lymph node status provides strong prognostic information in melanoma and is important for staging and treatment decisions. The National Comprehensive Cancer Network® (NCCN) recommends performance of sentinel lymph node biopsy (SLNB) for melanoma patients with a T category of ≥T2a. This study aims to assess our academic institution's guideline adherence to improve quality of care.

METHODS

Retrospective review of medical records from 2017 to 2023 identified 628 patients referred to our institution for invasive melanoma treatment. Adherence to guidelines was assessed using Chi-square analyses and Fisher's exact tests.

RESULTS

In total, 8.2% of cases did not follow the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) for SLNB. When justification provided within the medical record was considered adherent to guidelines, our rate of discordance was 1.6%. Head and neck melanomas were more likely to have guideline-discordant SLNB management, regardless of whether or not a justification was provided.

CONCLUSION

Greater than 98% of melanoma cases at our institution aligned with the SLNB NCCN Guidelines®. We outlined the complex justifications physicians and patients may use to pursue care that is nonadherent to guidelines. Employment of SLNB may be limited by medical comorbidities, surgical risks, and when the management would not change based on the result. Our study provides a blueprint for institutional assessment of guideline adherence and highlights the importance of documentation and guideline dissemination.

Digital spatial proteomic profiling reveals immune checkpoints as biomarkers in lymphoid aggregates and tumor microenvironment of desmoplastic melanoma

BACKGROUND

Desmoplastic melanoma (DM) is a rare melanoma subtype characterized by dense fibrous stroma, a propensity for local recurrence, and a high response rate to programmed cell death protein 1 (PD-1) blockade. Occult sentinel lymph node positivity is significantly lower in both pure and mixed DM than in conventional melanoma, underscoring the need for better prognostic biomarkers to inform therapeutic strategies.

METHODS

We assembled a tissue microarray comprising various cores of tumor, stroma, and lymphoid aggregates from 45 patients with histologically confirmed DM diagnosed between 1989 and 2018. Using a panel of 62 validated immune-oncology markers, we performed digital spatial profiling using the NanoString GeoMx platform and quantified expression in three tissue compartments defined by fluorescence colocalization (tumor (S100+/PMEL+/SYTO+), leukocytes (CD45+/SYTO+), and non-immune stroma (S100-/PMEL-/CD45-/SYTO+)).

RESULTS

We observed higher expression of immune checkpoints (lymphocyte-activation gene 3 [LAG-3] and cytotoxic T-lymphocyte associated protein-4 [CTLA-4]) and cancer-associated fibroblast (CAF) markers (smooth muscle actin (SMA)) in the tumor compartments of pure DMs than mixed DMs. When comparing lymphoid aggregates (LA) to non-LA tumor cores, LAs were more enriched with CD20+B cells, but non-LA intratumoral leukocytes were more enriched with macrophage/monocytic markers (CD163, CD68, CD14) and had higher LAG-3 and CTLA-4 expression levels. Higher intratumoral PD-1 and LA-based LAG-3 expression appear to be associated with worse survival.

CONCLUSIONS

Our proteomic analysis reveals an intra-tumoral population of SMA+CAFs enriched in pure DM. Additionally, increased expressions of immune checkpoints (LAG-3 and PD-1) in LA and within tumor were associated with poorer prognosis. These findings might have therapeutic implications and help guide treatment selection in addition to informing potential prognostic significance.

Pure and Mixed Variants of Desmoplastic Melanoma: A Single-Center, Retrospective, Clinicopathologic Review

BACKGROUND

Desmoplastic melanoma (DM) is a rare melanoma variant. Prognostic indicators and survival vary widely and are further confounded by the histopathologic distinction between pure DM (pDM) and mixed DM (mDM) subtypes. The utility of current treatment guidelines is limited by the lack of evidence-based recommendations.

OBJECTIVE

To compare the clinicopathologic characteristics of pure and mixed subtypes of DMs.

METHODS

All cases of DM were identified from the Washington University in St Louis institutional pathology database between January 2000 and September 2022. Fifty-two cases were identified and subsequently categorized as pure ( n = 26) or mixed ( n = 26). Clinical and histopathologic data were collected and compared.

RESULTS

There were no differences in demographics or tumor location between pure and mixed subtypes. Patients with mDM were more likely to have mitoses present ( p = .03). There were no differences in Breslow depth, tumor diameter, level of invasion, ulceration, and lymphovascular or perineural invasion. The utilization of sentinel lymph node biopsy ( p = .17) and sentinel lymph node positivity ( p = .67) were also similar.

CONCLUSION

Despite histopathologic distinction between pDM and mDM, these subtypes were found to have similar clinicopathologic characteristics, including similar rates of sentinel lymph node metastasis.

Neurosarcomatous amelanotic transformation of malignant melanoma presenting as malignant periopheral nerve sheath tumor: Rare case report

RATIONALE

Malignant melanoma (MM) is notorious for its remarkable morphological variation and aberrant histopathological patterns. In addition, Malignant Periopheral Nerve Sheath Tumor (MPNST) is an uncommon but aggressive soft tissue sarcoma. Because of the common embryological origin of melanocytes and Schwann cells in the neural crest, discriminating between a particular type of MM and MPNST can be difficult, particularly when they are amelanotic. Our goal is to increase awareness among clinicians of the rare variations of MM and the importance of medical history in improving the accuracy of the final clinical diagnosis.

PATIENT CONCERNS

A 68-year-old man was admitted to the hospital due to pain in his right ankle, which had persisted for 8 months, along with swelling for 4 months. Medical history revealed delayed healing of right plantar for 5 years after a traumatic injury.

DIAGNOSES

The ankle mass was initially diagnosed as MPNST through biopsy. After reviewing the patient's medical history and receiving the final pathological report following amputation, we have revised the diagnosis to metastatic amelanotic desmoplastic melanoma in the ankle part and lentigo maligna melanoma in the plantar part. This is due to both lesions displaying positive markers or mutated genes in immunohistology and Gene Mutation Detection, indicating homology between the 2 tumors.

INTERVENTIONS

Due to the malignant characteristics of the tumor and the patient's wishes, amputation of the right lower leg was carried out.

OUTCOMES

Subsequently, the patient was treated with interferon-γ and immunosuppressant PD-1 inhibitor, and survived for 1 year after amputation.

LESSONS

Clinical data, immunohistochemisty biomarkers and genes detection results can serve as valuable evidence for pathologists and clinicians in identifying the disease process. Collaborative efforts between clinicians and scientists are crucial in order to identify specific markers that can effectively differentiate between the 2 tumors, thereby enhancing the conclusiveness of the diagnosis.

Role of Sentinel Lymph Node Biopsy for Skin Cancer Based on Clinical Studies

The sentinel lymph node is the first lymph node from the primary tumor. Sentinel lymph node biopsy (SLNB) is a surgical procedure that can detect occult nodal metastasis with relatively low morbidity. It may also have a therapeutic effect via regional disease control. The Multicenter Selective Lymphadenectomy-I (MSLT-I) trial revealed a prognostic benefit from SLNB in melanoma patients. However, it remains unclear whether there is a prognostic benefit from SLNB in patients with nonmelanoma skin cancer owing to a lack of randomized prospective studies. Nevertheless, SLNB provides important information about nodal status, which is one of the strongest factors to predict prognosis and may guide additional nodal treatment. Currently, SLNB is widely used in the management of not only patients with melanoma but also those with nonmelanoma skin cancer. However, the utilization and outcomes of SLNB differ among skin cancers. In addition, SLNB is not recommended for routine use in all patients with skin cancer. In this review, we provide a summary of the role of SLNB and of the indications for SLNB in each skin cancer based on previously published articles.