Hurler's Disease with Multiple Atypical Mongolian Spots

Sir,

Extensive and abnormal presentations of birthmarks are often a clue to an underlying systemic disorder. We report the case of a 3-day-old neonate, in whom such a presentation resulted in the diagnosis of an inborn error of metabolism (IEM). The neonate delivered full term and vaginally, presented with multiple round-to-ovoid bluish noninfiltrated macules over the lower back, buttocks, thighs and left scapula, suggestive of extensive and aberrant Mongolian spots (MSs) [Figure 1]. A small dark bluish-black macule was evident within the large MS over the right lower back (“MS within MS”). Facial examination revealed multiple erythematous macules over the eyelids and pinnae, suggestive of salmon patches [Figure 2]. Further examination revealed normal anthropometry with the absence of facial dysmorphism. There was no history of seizures. Muscle tone and reflexes were preserved. There was no hepatosplenomegaly. Perinatal and family histories were insignificant with no consanguinity in parents. Ophthalmological and neurological evaluations were normal. Histopathology from scapular lesion revealed the presence of melanin-loaded fusiform melanocytes in mid-to-lower dermis, scattered between collagen bundles, consistent with MS. Skeletal radiographs of the skull, spine and limbs, abdominal ultrasound and computed tomography of the brain were unremarkable. Peripheral blood smear revealed vacuolated lymphocytes. Urinalysis for glycosaminoglycans confirmed mucopolysacchariduria. The enzyme α-L-iduronidase was undetectable in plasma on enzyme assay, confirming the diagnosis of Hurler's disease. The child was referred to a clinical geneticist for genetic evaluation and treatment with enzyme replacement therapy.

Figure 1.

Extensive and aberrant Mongolian spots over the lower back, buttocks, thighs, and left scapula. A small dark bluish-black macule (white arrow) is visible within the larger lesion over the right lower back (“Mongolian spots within Mongolian spots”)

Figure 2.

Salmon patches over the face (white arrow)

MSs are bluish-black birthmarks over the gluteal region, more commonly encountered in African or Asian population. Although spontaneous lightening is expected, atypical presentations of MS are markers of persistence and often suggest an underlying IEM[1,2] Atypical MS includes (1) multiple and extensive MS, (2) extrasacral or “aberrant” MS, (3) deeply pigmented MS, and (4) “MS within MS.” The IEMs typically associated with atypical MS are mucopolysaccharidosis (MPS), most commonly MPS-I or Hurler's disease followed by GM1 gangliosidosis.[2,3]

Children with MPS often have no clinical signs at birth. Features typical of MPS such as dysmorphic facies, skeletal dysplasia, ocular abnormalities, hepatosplenomegaly, developmental delay and neuromuscular deficits appear in the first 6–12 months. Vacuolation of lymphocytes on peripheral smear and mucopolysacchariduria are suggestive, and deficient blood levels of lysosomal enzymes are confirmatory.[4] Targeted mutation analysis of IDUA gene is needed for confirmation of the diagnosis of Hurler's syndrome and detection of familial carriers, respectively. Ancillary evaluation for systemic involvement is essential in an established case.

Despite this neonate not having any clinically apparent signs of Hurler's Syndrome, laboratory results confirmed it. Since atypical MS is now a well-established cutaneous marker of underlying MPS, this report reiterates the significance of such association. This is also the first report of such an association from India. Although this child had additional salmon patches, it is premature to comment on the additional significance of the presence of these vascular birthmarks. Since MPS-associated irreversible organ damage is preventable only by early administration of enzyme replacement and/or other therapies, recognition of cutaneous markers like atypical MS may prove to be life-saving for such children.

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Conflicts of interest

There are no conflicts of interest.