To the Editor:
We read the case report entitled “Metastatic cellular blue nevus: a rare case with metastasis beyond regional nodes” published recently in this journal.1 The authors described a 35-year-old man with 3 nodular lesions, namely a subcutaneous nodule in his left hand, a second nodule in his left axilla, and a third nodule in his left infraclavicular area. According to the authors, the 3 nodules were excised and showed identical histopathological features. After thorough histological, immunohistochemical, and array-based comparative genomic hybridization analysis, the authors interpreted this case as a cellular blue nevus in the hand with metastasis to both axillary and infraclavicular lymph nodes.
As we know melanocytic nevus, a totally benign lesion, does not metastasize. In tumor pathology, metastasis is one of the defining attributes of malignant neoplasm and only malignant neoplasm is capable of producing metastasis. Thus, metastatic nevus clearly is an illogical and confusing term and should not have been used in the first place. In this regard, we would like to point out 2 previous articles, one by Ackerman and Tang in 20032 and the other by Mones and Ackerman in 2004,3 in which illogical terms such as “benign metastasis,” “atypical blue nevus,” “malignant blue nevus,” and “metastasizing blue nevus” were criticized thoroughly and refuted completely.
In this case described by Bui et al,1 if the lesions are truly benign, namely cellular blue nevus, then the lesions in both axillary and infraclavicular lymph nodes simply represent nodal cellular blue nevi, not metastases. However, if the lesions in both lymph nodes are truly metastases, then the subcutaneous lesion in the hand has to be a melanoma. There is no such thing called “metastatic cellular blue nevus,” in our opinion.
1. Bui J, Ardakani NM, Tan I, et al. Metastatic cellular blue nevus: a rare case with metastasis beyond regional nodes. Am J Dermatopathol. 2017; doi: 10.1097/DAD.0000000000000834. [epub ahead of print].
2. Ackerman B, Tang P. Benign Metastasis. Dermatopathology: Practical and Conceptual [serial online]. Vol 9. 2003. Available at: Derm101.com
. Accessed March 15, 2017.
3. Mones JM, Ackerman AB. “Atypical” blue nevus, “malignant” blue nevus, and “metastasizing” blue nevus: a critique in historical perspective of three concepts flawed fatally. Am J Dermatopathol. 2004;26:407–430.