Griscelli Syndrome Workup

Updated: Jan 14, 2020
  • Author: Saud A Alobaida, MBBS, FRCPC; Chief Editor: Dirk M Elston, MD  more...
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Workup

Laboratory Studies

Genetic analysis can be performed to detect mutations in MYO5A, RAB27A, and MLPH.

For Griscelli syndrome (GS) type 2, laboratory features include pancytopenia, hypofibrinogenemia, hypertriglyceridemia, and hypoproteinemia, which can be seen with hemophagocytic syndrome (HS). In some patients, secondary hypogammaglobulinemia, impaired major histocompatibility complex–mediated cytotoxic effects, a decreased capacity of lymphocytes to trigger a mixed lymphocyte reaction, or various functional granulocytic abnormalities can be found. One report noted low levels of immunoglobulin G2 in a patient with Griscelli syndrome type 2.

Evidence of hepatitis can be demonstrated by abnormal liver function results. Neonatal hyperbilirubinemia (peak total bilirubin 26.5 mg/dL at age 4 wk) has been reported.

A prospective survey of degranulation assays for the rapid diagnosis of Griscelli syndrome type 2 and other familial hemophagocytic syndromes shows that such testing has promise. [49]

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Imaging Studies

Both CT and MRI of the head can be used to assess Griscelli syndrome (GS). Usually, findings are normal at birth. When the disease manifests, imaging findings become abnormal. Findings differ in the two variants Griscelli syndrome type 1 and type 2.

In Griscelli syndrome type 1, isolated congenital cerebellar atrophy was observed. No evidence of infiltration of lymphocytes is present in these patients.

In Griscelli syndrome type 2, CT scanning can show areas of coarse calcification in the globi pallidi, left parietal white matter, and periventricular and left brachium pontis. They can manifest as hypodense signals in the genu and posterior limb of the internal capsule on the right side (which is compatible with inflammatory changes), as well as posterior aspects of both thalami, together with minimal generalized atrophy. CT scanning can also suggest cell infiltration of the brain.

When HS manifests in Griscelli syndrome type 2, abdominal ultrasonograms can show hepatosplenomegaly with intrahepatic cholestasis and absence of bile duct distension.

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Other Tests

Transmission electron microscopy of the skin shows an accumulation of numerous normal-sized stage IV mature melanosomes in the cytoplasm of melanocytes, with virtual absence of such melanosomes in adjacent keratinocytes.

The peripheral blood smear shows no giant cytoplasmic granules in leukocytes. These findings allow Griscelli syndrome (GS) to be distinguished from Chédiak-Higashi syndrome (CHS).

Nonspecific electroencephalographic patterns can be seen in Griscelli syndrome type 2. [50]

Polarized light microscopy of the hair shafts aids in the differential diagnosis of CHS and Griscelli syndrome. [51, 52, 53]

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Procedures

Biopsy specimens of internal organs can reveal abnormalities. Liver biopsy specimens can show marked portal inflammation with focal hepatocellular necrosis.

Bone marrow aspiration samples can reveal slight hypocellularity with mild erythroid hyperplasia and hemophagocytosis.

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Histologic Findings

The common histopathologic findings of Griscelli syndrome (GS) include prominent, mature melanosomes in skin and hair follicle melanocytes.

Griscelli syndrome demonstrates hyperpigmented basal melanocytes and sparse pigmentation of adjacent keratinocytes. This pathology of melanocytes and keratinocytes leads to large, clumped melanosomes in hair shafts, and, as a result, the hair has a silvery-gray sheen. These results can be highlighted in Fontana-Masson–stained sections. Light microscopy shows large, irregular aggregations of melanin pigment in hair. In contrast, CHS pigment aggregates are regular and resemble natural white hair.

Electron microscopic examination of the skin shows many mature melanosomes in melanocytes accompanied by few melanosomes in adjoining keratinocytes. [34]

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