Pregnancy-associated melanoma epidemiology

to SSM type melanoma when matched for tumor thickness, probably due to its high tumor mutational burden.Methods: A 67-year-old man presented to our melanoma clinic for a follow-up examination after the excision of a melanoma the year before.No atypical pigmented lesions were detected clinically or dermoscopically.However, the patient presented a barely pinkish, infiltrated, non-scaling plaque of about 1 cm on the back of the hand, which had appeared 6 months earlier and seemed to be evolving.Dermoscopy showed shiny white streaks and dotted vessels but no pigmentation, and the lesion was biopsied for suspicion of squamous cell carcinoma (Bowen).Results: Surprisingly, histopathology displayed the typical features of a pure desmoplastic melanoma.The epidermis was normal while the dermis presented an asymmetrical, poorly demarcated proliferation of atypical, pleomorphic spindle-shaped melanocytes and a peritumoral lymphohistiocytic infiltrate.Tumor cells were positive for S100, SOX-10 and 5-HMC, and focally weakly positive for Melan-A.About 5% of cells were positive for MIB-1.Notably PRAME, BRAF, HMB-45, CD34, Factor XIII, CD10, ERG, desmin, LU-5, AML and p63 immunostains were negative.The Breslow was 1.7mm.A complete excision was rapidly organized, which confirmed the diagnosis and the Breslow, as well as the absence of neurotropism.The subsequent staging evaluation (CT, sentinel lymph node biopsy) and re-excision with 2 cm margins were negative, giving a final stage of IB.No recurrence has been observed at his 9-month examination.Conclusions: This case-report highlights the difficulty in the clinical diagnosis of early desmoplastic melanoma and stresses the importance of questioning patients for any skin change or new lesions.Indeed, in our patient, the malignant dermoscopic criteria, albeit aspecific (shiny white streaks and dotted vessels), in a relatively recent lesion, was the only basis for biopsy.