Giant melanosomes in the B‐K mole syndrome

Abstract

Giant melanosomes were identified in lentigines and nevi of 4 patients from 3 kindreds with the B-K mole syndrome. They were present in some dysplastic lesions but not in malignant melanomas. In one case examined in the electron microscope, characteristic ultrastructural features were observed.

Giant Melanosomes in the Dysplastic Nevus Syndrome

“…Although, as we have noted, the histolog ical features of the dysplastic nevus syndrome have been described in detail, GM have been described in only one report [7], Our find ings, together with those of Burgess et al [7], ofGM in both dysplastic and nondysplastic pigmented lesions from patients with dys plastic nevus syndrome support the hy pothesis that these patients may have a more generalized, basic defect in melanogenesis which seems not to be directly related to malignant transformation. Whether the de fect resulting in these GM is genetically re lated to the dysplastic nevus syndrome or whether it is transmitted independently can only be determined by studying clinically unaffected members of this and other dys plastic nevus families and pigmented lesions from nonfamilial sporadic cases.…”

“…Internally they con tained numerous vesicles, but lacked the structural protein filamentous scaffolding normally present within melanosomes ( fig. 2, insert); thus, these GM most closely resemble those which have been described in 4 other patients with dysplastic nevus syn drome [7], the leopard syndrome [2], and oc ular albinism [6].…”

“…Recently, Burgess et al [7] described GM in 4 patients from three kindreds with dys plastic nevus syndrome. As in ourcascs, GM were present in compound nevi, dysplastic nevi, intradcrmal nevi, junctional nevi, and lentiginous lesions.…”

“…The conditions include: nevus spilus [1], leopard syndrome [2], Albright's syndrome [3], xe roderma pigmentosum [4], neurofibromato sis [5], and ocular albinism [6]. Recently Burgess et al [7] found GM in 4 patients with dysplastic nevus syndrome. GM are al so present in a few nonhuman models in cluding the Aleutian mink [8], beige mouse [9], and Long-Evans rat [10], Although by light microscopy the GM in each of these conditions are similar, ultrastructurally they show variable morphologies depending on the subjects studied; from these data a varie ty of theories explaining their possible origins and biological significance have emerged [5, 1 1, 12].…”

“…Biopsies of pig mented lesions from 3 members of this fam ily, including clinically benign lentigines, typical nevi, and dysplastic nevi were noted to demonstrate GM. This association of GM with the dysplastic nevus syndrome provides the basis for this report; the ultrastructural features of these GM in 2 of these patients will be compared to those found in the 4 pa tients described by Burgess et al [7] and to GM found in other settings.…”