Discussion
The diagnosis of BCH is made on clinical grounds. Diagnostic criteria
are the manifestation in early childhood (average 15 months), the
typical clinical morphology and the predominant distribution in the head
and neck region. However, contrary to its original designation as benigncephalic histiocytosis, several recent case reports have shown
that extracephalic skin involvement, particularly on the upper trunk, is
also commonly found. (2-4)
BCH is a benign disease without systemic involvement that runs a
self-limited course. The lesions usually resolve within 50 months with
occasional mild atrophy and hyperpigmentation. (3, 5) Recently,
improvement of skin lesions has been reported in a 5-year-old boy with
extensive, progressive BCH involving the face, trunk and extremities
after twice-daily treatment with topical 1% rapamycin. (6)
Clinical differential diagnoses include Langerhans cell histiocytosis
(LCH) and the two prevailing types of NLCH, juvenile xanthogranuloma
(JXG) and generalized eruptive histiocytosis (GEH). LCH is a rare
cutaneous disease that usually presents with treatment-resistant
eczematous lesions on the scalp and/or intertriginous sites resembling
seborrheic or diaper dermatitis. LCH may take a malignant course and
affect other organs such as the lungs, liver or hematopoietic system. It
can be differentiated from NLCH by immunohistochemistry, which reveals
positive staining for the Langerhans cell makers S100, CD1a and
langerin. (3)
JXG is characterized by many small pink to red–brown, dome shaped
papules scattered on the upper part of the body that rapidly become
yellow (micronodular JXG) or by a few nodular lesions (large nodular
JXG). JXG mostly occurs in infants or young adults and may be associated
with extracutaneous involvement of the eyes, liver and lung. An
association with neurofibromatosis I, juvenile chronic myelomonocytic
leukemia and LCH has also been described.
GEH typically affects adults and presents as recurrent crops of
generalized numerous red to brown papules with a widespread
distribution. GEH can be associated with hematological neoplasia.
Clinical and histopathological distinction between an early phase of
small nodular JXG or GEH and BCH may occasionally be difficult or even
impossible. Thus it has been proposed that these diseases might be
variants of a single clinical entity. (7-9)
In the present case the diagnosis of BCH was based only on clinical
criteria that included a disease onset in early childhood (on average 15
months), the typical clinical morphology of the lesions and their
predominant distribution in the head and neck region. If feasible,
however, a skin biopsy should always be obtained to allow for
differentiation from other types of cutaneous histiocytosis.
In summary, our case brings to attention the clinical characteristics of
BCH and points to the fact that BCH may not be confined to the cephalic
region. We also discuss the distinction of BCH from other types of NLCH
and underline the benign course of this disease, which does not require
an extensive diagnostic work-up but only a regular clinical monitoring.
Author Contributions:
All authors have made substantial contributions to conception and
design, or acquisition of data, or analysis and interpretation of data;
and have been involved in drafting the manuscript or revising it
critically for important intellectual content; and have given final
approval of the version to be published. Each author has participated
sufficiently in the work to take public responsibility for appropriate
portions of the content; and agreed to be accountable for all aspects of
the work in ensuring that questions related to the accuracy or integrity
of any part of the work are appropriately investigated and resolved.