History
13-month-old boy. Nodular mass in the scalp.
Pathology
The specimen consists of a fragment of skin measuring 0.7 x 0.5
x 0.5 cm with some hair on the surface. The cut-section shows
an orange-yellow nodular lesion measuring 0.4 cm in diameter.
The dermis of this cutaneous fragment is infiltrated by a mixed
population of inflammatory cells lymphocytes, eosinophils, few
foamy histiocytes and scattered Touton giant cells. The overlying
epithelium is unremarkable. The lesion is well demarcated but
not encapsulated.
Discussion
The first patient with JXG was described in 1905 by Adamson who
named this entity «congenital xanthoma multiplex ».
Mc Donagh introduced the term «juvenile xanthoma»
to reflect the xanthomatous nature of the lesion. But when Helwig
and Hackney recognised the origin of this proliferation of lipid-laden
histiocytes and giant cells, they called it «juvenile xanthogranuloma».
JXG is actually considered a member of the non-Langerhans cell
group of histiocytic proliferative disorders.
It usually presents as an eruptive lesion of the head, neck and
upper trunk as a red or brown papule, nodule, macule or plaque.
Extracutaneous localisations have been described (visceral or
CNS).
An uncommon cutaneous subtype is the giant JXG, a lesion larger
than 2 cm in diameter occurring in children of 14 months of age
or younger with a strong female predominance (1M :5F) and a benign
course.
Generally JXG occurs in childhood and infancy (rare in adults)
with a relapsing course and spontaneous regression leaving a
flat, atrophic area of altered pigmentation. There is no sex
predilection and no familial transmission.
Visceral lesions have been described in lungs, bone, gonads,
gastrointestinal tract, kidneys, pericardium and eyes. Some association
with other medical conditions (neurofibromatosis, Niemann-Pick
disease, urticaria pigmentosa, myelogenous leukaemia) have been
reported.
Clinically, it must be differentiated from Spitz naevus, urticaria
pigmentosa, xanthomas, amelanotic melanoma, but the most important
differential diagnosis is the Langerhans’cell histiocytosis
(LCH).
