Incidental detection of non-melanoma neoplasms in sentinel lymph node biopsy for melanoma staging: A retrospective case series

Background

Patients with malignant melanoma have an increased risk of developing secondary hematologic malignancy, and patients with hematologic malignancies have an increased risk of developing melanoma. Rarely, sentinel lymph node biopsies (SLNBs) collected for melanoma staging might harbor lymphoma or even carcinoma, which may represent a second primary malignancy (SPM). Biopsied lymph node(s) might serve as the first site of recognition for a SPM. Yet, there has been little systematic investigation regarding the characteristics of incidental SPMs detected on SLNB for melanoma staging.

Methods

A series of cases of lymphomas and carcinomas were detected incidentally during SLNB for melanoma staging from two tertiary academic centers between 2000 and 2021.

Results

Fifteen cases of incidentally detected SPMs were reviewed, comprising 12 lymphomas and three carcinomas. The most common incidentally detected second malignancy was chronic lymphocytic leukemia/small lymphocytic lymphoma (60%, 9/15). There were three cases of incidentally detected metastatic carcinoma. Of all incidentally detected malignancies, 2/3 carcinomas and 4/12 lymphomas represented first-time diagnoses of SPM in a melanoma patient. Forty percent of cases (6/15) also harbored metastatic melanoma in the sentinel lymph node.

Conclusions

It is possible to incidentally detect SPMs in SLNBs for melanoma staging. Early detection of SPMs in melanoma patients has implications for the treatment of both incidental SPM and melanoma.