Xanthoma disseminatum.

Xanthoma disseminatum is a rare, benign, normolipemic form of non-Langerhans cell histiocytosis affecting the skin and mucous membranes. The cutaneous manifestations consist of hundreds of papules that are red – brown at first and then become yellowish. The papules symmetrically involve the eyelids, trunk, face and proximal extremities and in flexures and folds, tend quickly to merge, forming soft plaques. It is frequently associated with diabetes insipidus. Biopsy specimens show a mixture of histiocytes, foam cells, and inflammatory cells. Later, foam cells predominate and Touton giant cells are frequently present. This chronic disease has no known established treatment.

Mycosis fungoides: cutaneous T-cell lymphoma.

Mycosis fungoides (MF) is the most common group of cutaneous T-cell lymphomas. It is a rare non-Hodgkin’s lymphoma of mature, skin-homing, clonal, malignant T lymphocytes, usually observed in mid to late adulthood, that initially presents in the skin as patches, plaques, tumors, or generalized erythema (erythroderma) and can involve the lymph nodes and peripheral blood. In this review, we survey the MF literature of the last decade and highlight the major trends.

Spectrum of Papillon–Lefevre syndrome.

Papillon–Lefevre syndrome is an extremely rare autosomal recessive disorder characterized by severe periodontal disease with hyperkeratosis and fissuring of the palms and soles. Periodontitis is severe and destructive affecting both deciduous and permanent dentitions associated with palmo-plantar hyperkeratosis. These manifestations usually appear in childhood between 1 and 4 years of age and deciduous teeth exfoliate within or at the age of six. Permanent teeth erupt normally but soon get affected by periodontal disease. Individual becomes edentulous within teenage. Hyperkeratotic lesions extend to knees and elbows. Some cases have shown inconsistent manifestations such as calcification of falx cerebri and choroid plexus, calcification of the dura, attachment of the tentorium, thumb nail dystrophy and hyperhidrosis.

Hydroa vacciniforme: a very rare photodermatosis.

Hydroa Vacciniforme (HV) is a rare, acquired and chronic paediatric disorder that is characterized by photosensitivity and recurrent crops of skin lesions on sun-exposed skin, such as the face, ears and hands that heal with vacciniforme scarring. The pathogenesis of HV is unknown. No chromosome abnormality has been identified so far. HV patients have no abnormal laboratory results. The histopathologic features are distinctive and demonstrate intraepidermal multilocular vesicles and cellular necrosis. Most cases remit spontaneously by late adolescence.

Reactive perforating collagenosis.

Reactive Perforating Collagenosis (RPC) is a rare disease of elimination of altered collagen through the epidermis. The disease exists in childhood form with autosomal recessive mode of inheritance and an adult form acquired in association with diseases such as Diabetes Mellitus (DM), Chronic Renal Failure (CRF), hypothyroidism, lymphoma, hyperparathyroidism, neurodermatitis, AIDS, pulmonary fibrosis, scabies and herpes zoster infection.