Difficulties in morphological diagnosis of melanocytic lesions: a case report

Introduction. Skin cancer is one of the most common malignancies, however melanoma accounts for only 1.8 % of all skin cancers. Melanoma is rare but aggressive tumor. Early detection and appropriate treatment of the tumor are critical and result in improved overall and recurrence-free survival rates. Histopathological reporting plays a critical role in guiding the surgical oncologist's treatment plan for melanocytic lesions. The experience and knowledge of the pathomorphologist are decisive in the future fate of the patient. Case description. We report a case of a 36-year-old female patient who presented with a pigmented lesion on the skin of the trunk. in the regional cancer center at her place of residence, she underwent surgical removal of this lesion with a surgical margin of about 1 cm. The histological diagnosis was reported as melanoma. Diagnosis of melanoma was also confirmed in another medical center that did not specialize in the treatment of patients with skin tumors, but the tumor thickness was changed to a smaller one. However, in the federal cancer center that specialized in the treatment of patients with skin melanoma, the diagnosis of melanoma was not confirmed. The patient was diagnosed with nevus. The paper discusses in detail the reasons for the erroneous diagnosis of a malignant neoplasm, indicating the stages of differential diagnosis. Conclusion. This clinical case demonstrates that a reference analysis of borderline melanocytic lesions under conditions of specialized cancer centers with experienced pathologists is required. We have described objective difficulties in pathomorphological diagnosis, which can additionally be aggravated by the absence of important clinical and instrumental information, artifacts during excision biopsy, macroscopic examination, and orientation of tissue fragments in the embedding paraffin block.