This is a multicenter, ambispective, low-interventional clinical study evaluating molecular genetic markers for non-invasive differential diagnosis of benign and malignant pigmented skin and mucosal neoplasms. In retrospective cohorts genetics markers will be identified. In prospective cohort non-invasive adhesive system will be tested to identify malignant or benign lesions with prespecified sensitivity and specificity compared to other non-invasive techniques (i.e. dermoscopy) and using histopathological examination as a "golden standard".

Inclusion Criteria:

Cohort 1 (retrospective):

• Histologically confirmed diagnosis of melanocytic neoplasm of the skin or mucous membranes (benign, malignant or with unclear potential);

• The presence of a paraffin block with a tumor suitable for molecular genetic analysis;

• Signed informed consent form for living patients (for deceased, signing of a consent form with legal representatives is not required);

• Patient's age is over 18 years for the period of inclusion in the study (at the time of signing the consent form for living patients or for the excision biopsy period for deceased patients);

• Known clinical data of the patient (gender, age, skin phototype), hereditary history, medical history and follow-up of treatment outcomes for at least 5 years

  2. Cohort 2 (retrospective):

• Histologically confirmed diagnosis of melanocytic neoplasm of the skin or mucous membranes (benign, malignant or with unclear potential);

• The presence of a paraffin block with a tumor suitable for molecular genetic analysis

• The presence of cytological preparations (at least 2 glasses) of the primary tumor with tumor material

• Signed informed consent form for living patients (for deceased, signing of a consent form with legal representatives is not required);

• Patient's age is over 18 years for the period of inclusion in the study (at the time of signing the consent form for living patients or for the excision biopsy period for deceased patients);

• A known medical history and follow-up of treatment outcomes for at least 6 months.

  3. Cohort 3 (prospective):

• Clinically (including any type of dermatoscopy or other non-invasive diagnostic methods) suspected diagnosis of malignant melanocytic neoplasm (or neoplasms) of the skin or mucous membranes (or lesion(s) with unclear malignant potential)

• The patient is scheduled to undergo an excision biopsy (or wide excision) of the neoplasm (s) of the skin or mucous membranes within 3 months from the date of inclusion in the study and the patient is able to tolerate this intervention;

• Signed Informed Consent Form

Exclusion Criteria:

Cohort 1:

• Unknown histological diagnosis (no information on the melanocytic nature of the neoplasm)

• Unsuitable for analysis paraffin block with a tumor or its absence

• Unknown history or lack of traceability after diagnosis within 5 years

• For the period of inclusion in the study (signing an informed consent form for living patients or an excision biopsy for deceased patients), the patient's age is under 18 years

  2. Cohort 2:

• Unknown histological diagnosis (no information on the melanocytic nature of the neoplasm)

• Unsuitable for analysis paraffin block with a tumor or its absence

• Unsuitable for analysis cytological preparations/smears (or the absence of tumor cells in cytological preparations)

• Unknown history or lack of traceability after diagnosis within 6 months.

• For the period of inclusion in the study (signing an informed consent form for living patients or an excision biopsy for deceased patients), the patient's age is under 18 years

  3. Cohort 3 (prospective):

• The patient is NOT scheduled to undergo an excision biopsy (or wide excision) of the neoplasm (s) of the skin or mucous membranes in the next 3 months since inclusion in the study OR the patient is not able to tolerate this intervention;

• The available morphological or cytological confirmation of the nature of the neoplasm (s) (benign or malignant), which (s) is planned to be removed in the framework of this study,

• Ulcerated neoplasms;

• Contact bleeding neoplasms;

• Non-melanocytic neoplasms;

• Neoplasms with an area of more than 5 sq. cm

• Neoplasms located subcutaneously or in soft tissues and, according to clinical signs, not associated with the skin

• Known allergy to any component of the applied adhesive system;

• Inability of the patient to follow the study procedures (including contacting the researcher during the follow-up visits) or other reasons that, in the opinion of the principal investigator, may become an obstacle for the patient to participate in the study