Acral Lentiginous Melanoma: A report of three cases

ABSTRACT

Acral lentiginous melanoma is a rare variant of malignant melanoma and is characterized by a lentiginous (radial) growth phase that evolves over months or years to a dermal (vertical) invasive stage. Clinical and pathological features were reviewed in 3 cases of acral lentiginous melanoma of the soles. The first case was a 59-year-old female. On gross examination, there was a black, nodular, round, and ulcerated mass, 1.5 x 1.5 cm, on the posterior portion of the left sole. This mass was accompanied by peripheral pigmented macules. Histologically, the macular lesion revealed the pattern of a lentiginous growth phase, with a diffuse hyperplasia of atypical melamocytes in the basal layer of the epidermis. In the vertical growth component, atypical melanocytes (predominantly spindle cell) infiltrated the dermis, showing level 3 invasion. The second case was a 47-year-old male. On gross examination, there was a dark brown to black, nodular, hemorrhagic and ulcerated mass, 7x7 cm, on the middle portion of the right sole. This mass grew radially into neighboring tissue. Histologically, the radial growth component revealed atypical melanocytes which were distributed in the basal portion of epidermis. In the vertical growth component, atypical melanocytes (spindle, round, or polygonal cells) infiltrated the dermis, showing level 4 invasion. The third case was a 87-year-old female. There was a formation of satellite pigmented macules, up to 2x0.5 cm, on the right sole. The color of macules was usually not uniform but was likely to be scattered radially, being grayish brown, bluish black, or black. Histologically, the peripheral, macular, hyperpigmented lesion revaled the pattern of a lentiginous growth phase. In the vertical growth component, atypical melanocytes (predominently polygonal cells) infiltrated the dermis, showing level 13 invasion.