An unusual presentation of Becker Nevus

ARTICLE

Auteur(s) : Carmelo Schepis¹, Maria Lentini², Pinella Failla³, Lucia Castiglia⁴, Marco Fichera⁴, Corrado Romano³

¹Unit of Dermatology Oasi Institute (IRCCS), Via Conte Ruggero, 73 – Troina (EN), Italy
²Department of Human Pathology University of Messina, Italy
³Unit of Pediatrics and Medical Genetics Oasi Institute (IRCCS), Troina, Italy
⁴Genetic Diagnostic Laboratory Oasi Institute (IRCCS), Troina, Italy

A sixteen-year-old male affected by coeliac disease and severe mental retardation came to our observation for the almost simultaneous occurrence, during the previous two years, of three large hyperpigmented maculae over his right forearm and, bilaterally, over the pretibial areas (figures 1A, B). The lesions were brown in colour, approximately 12 cm in size, with irregular indented borders. Fair scattered hairs were present over the maculae. Mild keratosis pilaris was also detectable on the upper and lower limbs.

We suspected a Becker Nevus (BN) and obtained consent for a punch biopsy to confirm the diagnosis. After local anaesthesia, a 3-millimiter punch biopsy specimen was obtained from the pretibial right lesion and processed for histopathological examination. Histological analysis revealed (figure 1C) mild squamous hyperplasia with acanthosis and hyperorthokeratosis. The basal layer showed heavy hyperpigmentation. In the slightly fibrous dermis, smooth muscle arrectores pilorum unrelated to cutaneous adnexa were visible. Thus, the clinical diagnosis of BN was histologically confirmed.

The patient presented with a phenotype characterized by dolichocephaly and relative macrocephaly, bulging forehead, micrognathia, crowded teeth, posteriorly rotated ears, downslanting palpebral fissures, hypoplastic toenails, generalized hypotonia, and a surgically corrected congenital heart defect. Cerebral MRI showed moderately dilated lateral ventricles, thin corpus callosum and a widened congenital retrocerebellar cerebrospinal fluid space with hypoplasia of the left cerebellar hemisphere. Generalized muscle hypotonia and hypoexcitable tendon reflexes were found in the neurological examination, while ophthalmic examination showed compound hypermetropic astigmatism, tortuous retinal vessels and intermittent exotropia of the right eye.

Because of the clinical features, the patient underwent array-CGH (Agilent CGH 44A) analysis in order to search for sub-microscopic chromosomal re-arrangements, which led to the detection of a de novo 1.8 Mb microdeletion in the q35.2-q35.3 region of chromosome 5 (figure 1D).

BN usually affects young males, it is commonly located over the trunk, including the scapular regions, shoulders, and anterior chest. Other areas are less commonly involved [1] and lower limbs are barely reported [2], although it may affect other regions of the body [3]. To date, in the international literature, BN has not been described on the pretibial areas and, additionally, our patient showed the lesion on the right forearm. He also was coeliac and affected by mental retardation. Moreover, the numerous clinical abnormalities were consistent with a genetic disease which was confirmed by the detection of a genomic deletion, which can be considered as pathogenic on the basis of data from the literature and from Copy Number Variation databases. Furthermore, several dysmorphic features and neurological abnormalities in our patient have already been reported in patients with a similar 5q deletion [4].

The term “Becker Nevus syndrome” (BNS) is used to indicate the association of a BN with ipsilateral hypoplasia of the chest or limb and several other musculoskeletal anomalies [5]. A large recently published survey of the disease underlined and reconsidered the clinical spectrum of BNS [6]. It is more frequently detectable in females than in males. The regional correspondence between BN and musculoskeletal anomalies induced the authors to affirm that BNS is due to a lethal gene surviving in mosaic form. Our patient does not fulfil the recommended criteria for the diagnosis of BNS but shows an unusually extensive and bilaterally systematized cutaneous involvement of atypical locations.

Acknowledgements

References

2 Alhusayen R, Kanigsberg N, Jackson R. Becker nevus on the lower limb: case report and review of the literature. J Cutan Med Surg 2008; 12: 31-4.

3 Al Aboud K, Al Hawsawi K. Becker nevus on the hand. Eur J Dermatol 2002; 12: 588.

4 Rauch A, Dörr HG. Chromosome 5q subtelomeric deletion syndrome. Am J Med Genet C Semin Med Genet 2007; 145C: 372-6.

5 Happle R, Koopman JJ. Becker Nevus Syndrome. Am J Med Genet 1997; 68: 357-61.

6 Danarti R, König A, Salhi A, Bittar M, Happle R. Becker's nevus syndrome revisited. J Am Acad Dermatol 2004; 51: 965-9.