Cellular blue nevus with atypia (atypical cellular blue nevus): a clinicopathologic study of nine cases

Abstract

Atypical cellular blue nevus (ACBN) has clinicopathologic features intermediate between typical cellular blue nevus (CBN) and the rare malignant blue nevus (MBN)/malignant melanoma (MM) arising in a CBN. Herein we report 9 cases of ACBN. The patients were caucasian (6 females and 3 males) with a mean and median age of 47/51 years. Two patients complained of recent changes and about half of these tumors were located on the buttocks or scalp, averaging 1.5 cm in diameter. Histologically, they were characterized by architectural atypia (infiltrative margin and/or asymmetry) and/or cytologic atypia (hypercellularity, nuclear pleomorphism, hyperchromasia, mitotic figures, and/or necrosis). Assessment of the expression of 3 tissue markers demonstrated rare solitary cell staining with oncogene product bcl-2, and a proliferative index of 23+/-19 and 39+/-30 cells/10 high power field with antibodies to PCNA and Mib-1, respectively. No significant differences were detected comparing the above levels of expression to a control group of 15 CBN; however, ACBNs tended to show a higher proliferative index by PCNA and Mib-1 as well as a significantly higher mitotic rate (1/10 HPF vs. 0; p=0.001). Analysis of DNA content showed DNA aneuploidy in both groups. Follow-up data on 9 of 9 patients showed 1 patient dead without disease and 8 alive without disease (mean/median follow-up 42/32 months, range 15-96 months). No patient during this follow-up time has experienced either a local recurrence or lymph node or visceral metastasis. These findings highlight the close resemblance of ACBN to the natural history of CBN. Nevertheless, many of the distinguishing histologic features of ACBN are also those of MBN. Because of these intermediate clinicopathologic features, ACBN warrant close scrutiny and long-term follow-up.

Oral Atypical Cellular Blue Nevus: An Infiltrative Melanocytic Proliferation

“…A summary by Tran et al [17] indicates that CBN tend to occur at a younger Fig. 7 Extension of small and large tumor nests into underlying fat Fig.…”

“…The CBN occur on the buttocks/lumbosacral region followed by the scalp, face and hand [2,23]. ACBN cases similarly affect the buttocks, scalp and the extremities [16,17,27] while MBN have somewhat greater propensity to affect the scalp [11]. Women are affected more often than men for CBN and ACBN whereas MBN affects men more frequently [1,17] but these differences are modest.…”

“…When unquestionably malignant features such as widespread necrosis, mitotic activity, atypical mitoses and marked cytologic atypia are juxtaposed next to an otherwise bland CBN, the diagnosis is straightforward. However, multiple reports in recent decades of tumors with features intermediate between CBN and MBN prompted the controversial [15] designation of ''atypical blue nevus'' or ''atypical cellular blue nevus'' (ACBN) [16,17]. While similar clinically and apparently biologically to CBN [17], discrete histologic criteria for ACBN are currently under debate even among expert dermatopathologists [18][19][20][21][22].…”

“…However, multiple reports in recent decades of tumors with features intermediate between CBN and MBN prompted the controversial [15] designation of ''atypical blue nevus'' or ''atypical cellular blue nevus'' (ACBN) [16,17]. While similar clinically and apparently biologically to CBN [17], discrete histologic criteria for ACBN are currently under debate even among expert dermatopathologists [18][19][20][21][22]. The most often cited histologic criteria include asymmetry, a deeply infiltrative and irregular border, mild cytologic atypia, and mitotic activity [2 mm 2 [17,18,23].…”

“…While similar clinically and apparently biologically to CBN [17], discrete histologic criteria for ACBN are currently under debate even among expert dermatopathologists [18][19][20][21][22]. The most often cited histologic criteria include asymmetry, a deeply infiltrative and irregular border, mild cytologic atypia, and mitotic activity [2 mm 2 [17,18,23]. Herein we describe, to our knowledge, the first oral case of a CBN exhibiting atypical architectural features along with complementary molecular data.…”