Giant polypoid mass on thigh: a child with nevus lipomatosus cutaneous superficialis.

To the Editor,

We describe a 6-year-old boy who presented to our out-patient clinic with an enlarging mass on his limb, which he had had since birth. Dermatological examination revealed skin-colored, polypoid, approximately 2.5cm elevated, large plaque, measuring 5x4cm, on the posterior of his right thigh (Figure 1). Furthermore, smaller, discrete, similar papules were located around the mass. Otherwise, body regions were normal. The patient's medical history was unremarkable and no family member had experienced a similar lesion. The large lesion was totally excised. Histopathological examination showed an acanthotic epidermis, flattening of retes, and mature adipocytes between collagen fibers in both the papillary and deep dermis (Figure 2). Drawing on clinical and histopathological findings, the patient was diagnosed with Nevus lipomatosus cutaneous superficialis (NLCS). At follow-up, the excision region healed with a cosmetically acceptable appearance.

Figure 1

Skin-colored, polypoid mass on the posterior of the right thighk

Figure 2

Mature adipocytes between collagen fibers in both the papillary and deep dermis (H&E, x10)

Nevus lipomatosus cutaneous superficialis is an idiopathic and benign cutaneous hamartoma of mature adipocytes, located in the dermal compartment. This tumoral lesion was first defined by Hoffman and Zuhrelle in 1921.[1] Hamartomas are very rare and sporadically observed in two clinical types: the classical multiple form (Hoffman-Zurhelle type), presenting as a plaque or mass consisting of grouped pedinculated and cerebriform nodules; and the solitary form with a single papule or nodule. The classical type may be congenital or emerge in the second or third decades of life.[1,2] The lesion may grow to reach a giant size. No familial history was defined. Nevus lipomatosus cutaneous superficialis is usually located on the buttocks, trunk and thigh, in a zosteriform, or in linear or segmental fashion. In this report, we describe a child with a large NLCS lesion whose medical history and dermatological features were typical. The striking finding was that the hamartoma had grown constantly in early life, from a small nodule to a large mass.

The typical histopathological feature of NLCS is mature adipocytes filling the papillary and deeper dermis, where they should not locate. [1] The very rarity of NLCS needs to be suspicious for diagnosis in patients presenting with papules, nodules or plaques, especially skin-colored ones. Clinical differential diagnoses include neurofibroma, nevus sebaceous, angiolipoma, acrocordons and intradermal melanocytic nevus, in which the typical histopathological features of NCLS facilitate differentiation. Although focal dermal hypoplasia is clinically different, it may resemble histopathologically NLCS with adipocytes in the dermis. However, collagen is lower in amount and loosely arranged.[3-5]

Treatment of NLCS is usually considered for the classical multiple type since it may grow to a large and disfiguring tumoral mass. Surgical excision of the entire lesion is the preferred approach.[2] Since the classical type may cause significant cosmetic problems, early diagnosis and excision are recommended in order to provide less invasive and simple management. In conclusion, NLCS should be included in the differential diagnosis of enlarging cutaneous tumoral lesions emerging at birth.