Dermoscopic findings and histological correlation of the acral volar pigmented maculae in Laugier-Hunziker syndrome

Laugier-Hunziker syndrome (LHS) is an acquired, benign, macular hyperpigmentation of the lips and oral mucosa, often associated with pigmentation of the nails. Volar acral maculae on the palms and fingertips of patients affected by LHS are a typical feature of this rare entity. Dermoscopic examination of these maculae has been described in a previous report, in which authors found a parallel-furrow pattern. We describe two cases in which a parallel-ridge pattern (PRP) was found on the dermoscopic examination of the pigmented acral lesions. Histological examination showed increased melanin in basal keratinocytes, which was most prominent in those located at the crista intermedia profunda, that is, in the epidermal rete ridges underlying the surface ridges. In our study, dermoscopic features of the pigmented maculae found on LHS differed from those previously described. In addition, by means of this case report, the histological features of these lesions are described for the first time, showing an excellent correlation with dermoscopy. The reported cases prove that although the PRP is very specific of melanoma, it is also possible to find it in benign lesions. Therefore, we must be familiar with the differential diagnosis of PRP, and take into consideration the clinical context in which we find it. Further studies are needed to increase our knowledge on the histological and dermoscopic features of acral pigmented maculae of LHS.     

Fluorescence in situ hybridization for distinguishing cellular blue nevi from blue nevus-like melanoma

Background: Blue nevus‐like melanomas are melanomas that arise in association with blue nevi or closely simulate the histopathologic appearance of a blue nevus, usually a cellular blue nevus (CBN). Although the majority of CBN can be readily distinguished from blue nevus‐like melanoma by conventional microscopy, there are a subset of cases where this distinction may be exceedingly difficult or impossible. Methods: In this study, we evaluated the ability of a fluorescence in situ hybridization (FISH) assay targeting 6p25 (RREB1), 6q23 (MYB), 11q13 (CCND1) and the centromere of chromosome 6 (Cep6) to distinguish between CBN and blue nevus‐like melanoma. We identified five cases of blue nevus‐like melanoma and 12 cases of CBN. Results: The FISH assay was performed with 100% sensitivity and 100% specificity. Three of five cases met the 6p25/Cep6 criteria, all five met the 6p25 gain criteria and three of five met the 6q23/Cep6 loss criteria. None of the cases met criteria for gains in 11q13. None of the 12 CBN met any criteria for melanoma. Conclusions: A combined analysis of clinical aspects, histopathologic changes and FISH analysis could potentially contribute significantly to the ability of pathologists to discriminate between blue nevus‐like melanoma and blue nevi in challenging cases. Gammon B, Beilfuss B, Guitart J, Busam KJ, Gerami P. Fluorescence in situ hybridization for distinguishing cellular blue nevi from blue nevus‐like melanoma.     

Assessment of the presence of mucosal human papillomaviruses in malignant melanomas using combined fluorescent in situ hybridization and chemiluminescent immunohistochemistry

BACKGROUND: The vast majority of studies aimed at detecting human papillomavirus (HPV) DNA in skin cancer have used sensitive polymerase chain reaction (PCR) methods but the PCR technique, despite its high sensitivity, is not suitable to ascertain whether (i) the presence of HPV can be related only to few cells harbouring the virus, (ii) the presence of HPV is due to a tumour surface contamination and (iii) the presence of HPV is localized in cancer cells, rather than in normal keratinocytes present in the tumour biopsy. In a recent work we have found mucosal high-risk (HR) HPV genotypes in primary melanoma by PCR. OBJECTIVES: To localize mucosal HR-HPV nucleic acids and tumoural melanocytic marker in the same sections of primary melanoma samples in order to understand the relationship between HPVs and melanoma cells. METHODS: We have developed a very sensitive method that combines an enzyme-amplified fluorescent in situ hybridization (ISH) for the detection of HPV nucleic acids (types 16 and 18) with a chemiluminescent immunohistochemistry (IHC) method for the detection of the tumoural melanocytic marker HMB-45 sequentially in the same section. Digital images of fluorescent ISH and chemiluminescent IHC were separately recorded, assigned different colours and merged using specific software for image analysis. RESULTS: The combined fluorescent ISH and chemiluminescent IHC demonstrated a sharp colocalization (in the range 60-80%) of HPV nucleic acids and melanoma marker inside the same sections of melanoma biopsies, with a strong specificity and sensitivity. CONCLUSIONS: The strong colocalization of mucosal HR-HPV nucleic acids and HMB-45 melanocytic marker emphasized that viral nucleic acids were specifically present in melanoma cells and supported a possible active role of HPV in malignant melanoma.