Case Report: Griscelli Syndrome ? A Unique Pigmentary Defect

Griscelli syndrome is a rare disorder with hypomelanosis of skin, silvery-gray hair due to abnormal melanosomal trafficking in melanocytes. It is caused by mutations in 3 genes MYO5A, RAB-27A, MLPH (Melanophilin) and accordingly classified into 3 subtypes GS1, GS2 and GS3 respectively. These 3 proteins interact and together form heterotrimeric complex responsible for intracellular vesicular transport and secretion. RAB27A is key effector of cytotoxic granule exocytosis. The feature common to all 3 variants is pigmentary dilution. GS1 patients have primary neurological disorder without immune defects, whereas GS2 group exhibit recurrent infections with hemophagocytosis. Agglomerates of mature melanosomes in hair shaft and skin microscopy, sparse pigmentation of adjacent keratinocytes, and absence of giant granules in neutrophils are diagnostic of GS. GS2 develop hemophagocytic syndrome characterized by uncontrolled activation of T lymphocytes, macrophages and generalized lymphohistiocytic infiltrates. Bone marrow transplantation remains only curative modality. We report a child with classical features of GS and pathognomonic histopathological features of skin and hair.