The significance of multiple blue-grey dots (granularity) for the dermoscopic diagnosis of melanoma

Abstract

Background: The presence of multiple blue-grey dots (MBGD) is widely used by clinicians to decide if a pigmented lesion should be removed, but only little is known about their significance.

Objectives: To evaluate the significance of MBGD for the dermoscopic diagnosis of melanoma.

Methods: In part 1 we retrospectively evaluated 340 pigmented lesions for the presence and morphological appearance of granularity. One hundred and seventy melanomas were included and matched with 170 benign and dysplastic naevi which were randomly chosen from our collection. In part 2, 3773 lesions were examined prospectively in at-risk patients: all lesions with granularity were recorded, surgically removed and subjected to histopathological examination.

Results: In part 1, granularity was found in 26.5% of the benign lesions and 93.5% of melanomas. The presence of granularity, granularity at the periphery, irregularly distributed granularity and granularity in association with red and white colour were statistically highly significant for the diagnosis of melanoma (P < 0.001). In part 2, granularity was found in 1.08% of the 3773 lesions and more frequently in sun-damaged skin. Sensitivity for the diagnosis of melanoma was 85% and specificity 99%.

Conclusions: After the revision of many lesions with MBGD, we concluded that the term 'granularity' better describes this entity. Lesions with irregular granularity (periphery, irregularly distributed) should be removed especially if they are associated with red, blue or white colour. Lesions with a benign dermoscopy pattern which have granularity with a regular appearance and involving only a small portion of the lesion do not require surgical excision.