ARTICLE
Solitary neurofibromas raise the question of their potential relation
to neurofibromatosis (NF). We report the case of an isolated, vulvar neurofibroma
in a young child. The incidence of this localisation and classification
of the lesion among NF is discussed.
Case report
A 17 month old girl presented with a nodular lesion of the vulva which
had been developing since the age of 2 months. On examination, a 2 x 1
cm lesion was found which was red-wine colored, smooth, mobile, and painless,
and localized to the left labium major (Fig.
1). No other skin abnormalities were noticed, in particular no
café au lait spots, freckling or other nodular lesions.
The patient was a first child, born after a normal pregnancy, with no
remarkable family history. Histologic examination revealed a mixed proliferation
of spindle shaped cells arranged in a loose, micro-fibrillar matrix surrounding
skin appendages and associated with the presence of mastocytes and numerous
nerve branches (Fig. 2).
Some of these cells expressed the S100 protein on immunohistochemical
analysis. Additionaly they were vimentin+, actin-, and factor VIII-. According
to these data, a diagnosis of vulvar neurofibroma was made. Differential
diagnoses such as fibromatosis, myofibromatosis, fibrous hamartoma or
rhabdomyosarcoma were ruled out by clinical and immunohistological examination.
Neurological and ophthalmologic examinations failed to detect any other
abnormalities. The presence of a heart murmur resulted in the diagnosis
of a moderate, atrio-septal defect visualized by echocardiography. Because
of the asymptomatic nature of the lesion and the young age of the patient,
surgery was ruled out. A regular follow-up was conducted and no other
sign of neurofibromatosis has appeared, 2 years later.
Discussion
Neurofibroma can be seen either solitary or in the context of neurofibromatosis.
Solitary, genital neurofibromas have been described and may present as
a giant, plexiform neurofibroma which may be responsible for dyspareunia
[1, 2]. In children, the involvement of the genital area is rarely reported
and is represented by either vulvar or more frequently clitoral involvment
where enlargement may simulate intersex states [3-11]. For these cases,
a genitourinary tract involvement must be eliminated by a cystoscopic
examination [12]. Some of these neurofibromas may remain isolated during
evolution [13, 14] which is currently the case for our patient. However,
a longer follow-up is necessary before any definite conclusion can be
drawn, especially because in children, lesions continue to appear from
birth (or later) to a more advanced age. The incidence of vulvar neurofibroma
in females with NF is variably considered: rare according to some authors
[1, 3], it appears rather frequently for Schreiber [15] who reported an
18% incidence among 53 female patients. In the majority of the reported
cases of genital neurofibromas, patients suffered from either type I or
V NF [16-18]. The presence of other typical lesions such as café
au lait spots, freckles or other neurofibromas was, in these cases,
of great help in the diagnosis.
Solitary lesions can be difficult to classify
among NF. Because of the clinical heterogeneity of this disease, Riccardi
proposed a classification of NF using VIII subtypes among which the type
V corresponds to segmental NF. Later, Roth suggested to further individualize
4 subsets of this type (Va, true segmental; Vb, localized, with deep involvement;
Vc, hereditary segmental; Vd, bilateral segmental). More recently, Combemale
et al. [19] suggested distinguishing three subgroups: hereditable
generalized neurofibromatosis (among which NF1 and 2 are the main types),
non-heritable segmental neurofibromatosis (localized lesions with a dermatomal
distribution), and non-heritable neurofibromatous hamartomas (lesions
appearing in a restricted body area but not dermatomal).
The localization of the lesion, the absence
of other cutaneous or visceral lesions and of family history lead us to
present this case as a vulvar, neurofibromatous hamartoma. The course
of genital neurofibroma can sometime be severe with transformation into
sarcoma or schwannoma when they are seen in the context of NF1 [20, 21].
Solitary lesions seem to follow a more benign course and no cases of transformation
have so far been reported. The treatment of such lesions is mostly surgical
but the possibility of recurrence justifies a prolonged and regular follow-up.
In our patient, surgery has been delayed because of her young age and
the absence of functional consequences.
CONCLUSION
Acknowledgements
We would like to thank Pr. Grosshans for his help concerning the histopathological
examination of the lesion.
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