Electron microscopy of lentigines was performed to study the pigmentation abnormality in two children with LEOPARD syndrome. Giant melanosomes similar to those seen in café-au-lait spots of neurofibromatosis and nevus spilus were found in a lentigine from one of our cases. Our results show that "spherical granular melanosomes" described in neurofibromatosis, are lysosomal-like structures associated with the development of complex melanin granules. Our study also demonstrates that immature melanosomes are present in some keratinocytes of LEOPARD syndrome. This finding is in contrast to the prevailing concept that only mature melanosomes are transferred to keratinocytes. The occurrence of individual melanosomes of normal size and shape in keratinocytes of skin in whites with LEOPARD syndrome, suggests that neither the size of melanosomes, nor the racial differences are the factors determining the distribution of melanosomes in keratinocytes.

A 73-year-old woman from Guyana had nodular keloidal lesions on her face which had persisted for 56 years. A biopsy of the lesion revealed lobomycosis, a rare fungal infection. Microscopically, numerous fungi were seen in giant cells and macrophages. The macrophages had abundant pink reticulated cytoplasm. These macrophages in lobomycosis, considered by some in the past to be granular myoblastoma cells, were rich in glycoproteins and appeared to be "Gaucher-like cells" in electronmicrographs. Further, a transition of macrophages containing organisms to Gaucher-like cells was noted. Antibodies to the fungus were demonstrated in the patient's serum by counter immunoelectrophoresis and indirect immunofluorescence studies. We postulate that the Gaucher-like cells formed because of the inability of host macrophages to digest glycoproteins in the capsule of this unusual fungus.