Search

A 17-year-old male presented with a large sebaceous naevus (SN) comprising part of his right face and scalp and a speckled lentiginous naevus (SLN) on his left trunk, hip, neck and scalp with a checkerboard pattern. His right oral hemimucosa showed extensive papillomatous lesions, which were contiguous with the upper-lip SN lesions. He also showed extracutaneous manifestations including cardiac, musculoskeletal and ocular alterations. Internally, he had developed two primary rhabdomyosarcomas. DNA samples of the SN, SLN, oral papillomatous hyperplasia and both rhabdomyosarcomas were analysed by Sanger sequencing. An HRAS c.37G>C mutation was detected in all of them. Skin and blood DNA were wild-type. Phacomatosis pigmentokeratotica (PPK) is characterized by the association of an SN with a papular naevus spilus and extracutaneous manifestations. Until recently, the aetiopathogenetic hypothesis of didymosis was accepted. However, in 2013 Groesser et al. proved the existence of an activating HRAS mutation as the cause of this syndrome. A higher incidence of cancer has been observed in germline RASopathies. Furthermore, up to 30% of human cancers show dysregulation of the Ras-Raf-MEK-ERK pathways. In our patient, an HRAS mosaic mutation explains not only the cutaneous but also the extracutaneous manifestations. To our knowledge this is the first described case of PPK in which the existence of an HRAS mosaic mutation is the confirmed cause of rhabdomyosarcoma. Furthermore, the HRAS c.37G>C mutation has never been related to any type of rhabdomyosarcoma. Mosaicisms could be underdiagnosed causes of childhood tumours. As dermatologists we stand in a privileged position of being able to detect these alterations., (© 2018 British Association of Dermatologists.)

Lichen myxoedematosus (LM), or papular mucinosis, is an uncommon papular eruption caused by the dermal deposition of mucin. Three clinical forms can be distinguished, namely localised, disseminated (involving more than one site), and generalised LM, the last is called scleromyxoedema, and demonstrates erythema and skin sclerosis. Paraproteinaemia, often consisting of an abnormal IgG with lambda light chains, is usually present in patients with LM. Visceral involvement has also been documented. An association between LM and human immunodeficiency virus (HIV) infection has been reported recently. We now describe two further HIV-positive patients with LM and present a review of the literature regarding this association.

An adult male was described, who developed a tumour on his left arm, which was diagnosed as a primary cutaneous extramedullary plasmacytoma after histopathological, electron microscopic and immunocytochemical studies. Further studies ruled out the presence of multiple myeloma, extramedullary plasmacytoma of another site, or paraproteinaemia/paraproteinuria. During a relapse of the tumour 2 1/2 years after initial treatment, a new immunocytochemical study demonstrated that the tumour cells expressed monoclonal lambda IgG at the intracytoplasmic level, an unusual finding.