We describe a 61-year-old woman who presented with multiple small, firm, shiny, skin-coloured papules in a symmetrical pattern on the dorsum of the hands, sides of the fingers and extensor aspect of the forearms. These had slowly increased in number over a period of 40 years, and were asymptomatic. Both laboratory results and systemic review were unremarkable. Histological examination of six papules revealed well-circumscribed but unencapsulated dermal nodules composed of epithelioid histiocytes and abundant alcian blue-positive mucin separating broad bundles of collagen. Histiocytes within the nodule stained positively with vimentin, and were focally positive for alpha1-antitrypsin and lysozyme. The interstitium was positive for tenascin. On electron microscopy, the histiocytes showed numerous circular, osmophilic myelin bodies and zebra bodies reminiscent of those seen in lysosomal storage diseases. Our patient's clinical, histological and ultrastructural features have been previously described as hereditary progressive mucinous histiocytosis, a rare familial form of eruptive histiocytoma characterized by multiple persistent papules with prominent mucinosis.

A 63-year-old man presented with an intensely pruritic vesiculo-bullous eruption on the limbs and was subsequently found to have an IgA kappa multiple myeloma. The eruption clinically and histologically was suggestive of linear IgA disease (LAD), dermatitis herpetiformis (DH), epidermolysis bullosa acquisita (EBA), or bullous lupus erythematosus (LE), with the skin biopsy revealing subepidermal bullae and dermal papillary micro-abscesses. However, direct immunofluorescence showed a unique pattern of diffuse dermal IgA staining. Although chemotherapy produced a dramatic resolution of the lesions, which paralleled the fall in serum IgA paraprotein level, the myeloma later became progressive and the resulting paraprotein increase was accompanied by recurrence of the eruption. We propose that this patient's rash was the presenting manifestation of his multiple myeloma, and was a consequence of transudation of IgA paraprotein into the dermis.

A 40-year-old woman with no pre-existing hepatic disease developed a cutaneous allergic reaction to intramuscular vitamin K1. She received this medication prophylactically prior to surgery, developed severe localized, and subsequently generalized, dermatitis, beginning 5 days after administration of the Konakion Cremophor-EL form of vitamin K1 by intramuscular injection at four sites on her thighs. Investigation by patch and intradermal testing revealed delayed-type hypersensitivity to Konakion Cremophor-EL, Konakion Mixed Micelles and pure vitamin K1, but not Cremophor-EL vehicle alone. This case is unusual because the patient was also shown to be patch test positive to vitamin K3 sodium bisulfite.

Plaster of Paris (POP) bandages are extensively used for splinting and casting injured or surgically repaired body parts. Allergic contact dermatitis caused by POP has been reported only rarely in the medical literature. An 81-year-old woman developed multiple large, tense, haemorrhagic bullae on the palm, and an acute vesicular eczematous eruption on the forearm, after the application of a POP splint. Subsequent patch testing revealed positive reactions to both the POP bandage used and to benzalkonium chloride, a component of the POP formulation. Patch tests to two other POP products without benzalkonium chloride were negative. These results confirm those of previous studies which have implicated the quaternary ammonium compound benzalkonium chloride as the allergen responsible for POP-induced allergic contact dermatitis.

A 28-year-old man in whom CD50 (Ki-1)-positive cutaneous large cell lymphoma manifested as multiple widespread ulcerated nodules; which developed over a 2-week period, is reported. The lymphoma was composed of large anaplastic cells in large clusters, with scattered eosinophils, neutrophils and small lymphocytes. Extensive staging investigations revealed no extra-cutaneous disease. No treatment was given because, within weeks of presentation, the nodules began to regress spontaneously and the patient remains disease-free 20 months later.