Case of nodal nevus with melanocytic cell aggregates in the lymphatic hilum: A potential diagnostic pitfall that requires differentiation from metastatic melanoma of the lymph node

A Disguising Fast-Growing Metachronous Melanoma and COVID-19

An unusual case of a 52-year-old female with two metachronous melanomas is presented. An atypical fast-growing nodular melanoma appeared 18 months after the complete excision of an in situ melanoma and one month afterward a SARS-CoV-2 infection. Intra-nodal melanocytic proliferations were identified during lymph node assessment, raising important diagnostic and prognostic concerns. No melanoma susceptibility genes were found. This case report raises the question about the COVID-19 immunosuppression effect on the tumor microenvironment and the oncogenic potential of SARS-CoV-2. It also highlights the importance of clinical follow-up in melanoma patients, which was significantly delayed during the COVID-19 pandemic.

Current concepts of ectopic nodal inclusions with special emphasis on nodal nevi

Nodal inclusions of ectopic tissue within lymph nodes are seen comparatively often in dermatopathology and general pathology. Glandular and nonglandular epithelium, as well as melanocytic nevi can be observed within lymph nodes and represent mostly incidental findings without any relevance. The main challenge in reporting these morphologic features is to differentiate such benign inclusions from metastatic settlements of distinct organ tumors. As sentinel node biopsy and lymph node dissection have become standard procedure in clinical oncology and have an immense clinical impact, the correct evaluation of these nodal inclusions is indispensable to avoid undertreatment or overtreatment of patients. In addition, the genesis of these inclusions has not yet been satisfactorily clarified. Two concepts have been laid out: the theory of benign metastases and the migration arrest theory. However, neither theory has so far been able to answer the following questions: Why do we find more nodal nevi in patients with melanoma who had a sentinel node biopsy than in patients without melanoma, and why do we not find nodal nevi in deep visceral lymph nodes? We present a comprehensive review of the current knowledge on nodal inclusions, proposing a concept for the pathogenesis of nodal nevi, to answer these questions.