Tumoral melanosis
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Synopsis
Tumoral melanosis is usually observed from completely regressed melanocytic proliferations, including a primary malignant melanoma. In these cases, it may appear at the site of the primary tumor or at sites of cutaneous metastases, and the phenomenon is often associated with the presence of metastatic melanoma. Most recently, melanoma-associated tumoral melanosis has been described in patients with metastatic melanoma undergoing immunotherapy, such as with talimogene laherparepvec, ipilimumab, nivolumab, and pembrolizumab, as well as dabrafenib and trametinib. In these patients, tumoral melanosis usually occurs nearby the primary melanoma excision site or at the site of prior in-transit metastases.
Tumoral melanosis has also rarely been observed after regression of pigmented epithelial lesions, such as pigmented basal cell carcinoma, pigmented Bowen disease, seborrheic keratosis, solar lentigines, pigmented epithelial lined cysts, and benign nevi. Other pathologies described in the literature associated with this finding include mycosis fungoides and blastic plasmacytoid dendritic cell neoplasm (BPDCN).
Even more rarely, tumoral melanosis has been reported in the lymph nodes, known as nodal melanosis. Anecdotally, it has also been found in the visceral organs of 2 patients.
Codes
ICD10CM:L81.4 – Other melanin hyperpigmentation
SNOMEDCT:
402612007 – Hypermelanosis due to neoplasia
Look For
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
The potential clinical and histologic differential diagnoses of causes of tumoral melanosis include other heavily pigmented melanocytic lesions, such as:- Animal-type melanoma (or other types)
- Deep penetrating nevus
- Epithelioid cell or cellular blue nevus and atypical variants (compound blue nevus)
- Blue nevus–like melanoma
- Pigmented epithelioid melanocytoma
- Pigmented spindle cell nevus (Reed nevus)
- Cutaneous melanocytic schwannoma (rare)
- Pigmented epithelioid cysts
- Pigmented basal cell carcinoma
- Squamous cell carcinoma
- Epithelioid cell or cellular blue nevus and atypical variants (compound blue nevus)
- Blue nevus–like melanoma
- Pigmented epithelioid melanocytoma
- Pigmented spindle cell nevus (Reed nevus)
- Melanoma
Best Tests
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Management Pearls
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Therapy
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Drug Reaction Data
Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.Subscription Required
References
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Last Reviewed:03/08/2023
Last Updated:03/09/2023
Last Updated:03/09/2023