A new variant of mastocytosis: report of three cases clinicopathologically mimicking histiocytic and vasculitic disorders.

Cutaneous mastocytosis (CM) or urticaria pigmentosa is characterized by abnormal proliferation and accumulation of mast cells. Clinically, CM usually presents as symmetrically distributed red-brown macules or papules that develop weals, erythema and often pruritus on stroking (Darier's sign). The histological hallmark of the disease is an increase in oval to spindle-shaped mast cells in the dermis located around blood vessels and skin appendages. We describe three patients with a new clinicopathological type of CM, which clinically mimics a histiocytic disorder and histologically mimics leucocytoclastic vasculitis (LV). Three infants (two boys and one girl) developed generalized reddish-yellow-brown macules of 3-10 cm with occasional scaling and crusting on the trunk and extremities without further symptoms or organ involvement except variable itching. Histology revealed diffuse and dense dermal infiltrates of eosinophils, neutrophils and nuclear debris with perivascular accentuation, imitating LV. This infiltrate masked large epithelioid cells, positive for macrophage markers, which by special histochemical stains for metachromatic granules turned out to be mast cells. This is the first report of this new variant of CM, which may cause considerable diagnostic difficulties both clinically and histopathologically.

A cluster of rotavirus enteritis in adult transplant recipients.

Diarrhea following solid organ transplantation is a common side effect of some immunosuppressive agents but can also be caused by many pathogens. An outbreak of rotavirus (RV) enteritis presenting with severe diarrhea in four solid organ recipients was analyzed. The first case was diagnosed in a 6-month-old liver recipient who was prehospitalized on a pediatric ward. Within 1 month, three adult patients (two liver, one renal recipient) presented with enteritis. During diarrhea a significant rise in tacrolimus levels was observed. One patient developed toxic megacolon with ulcerative colitis. Infections were self-limiting but led to secondary infectious complications and prolonged hospitalization. This is the first reported outbreak of RV enteritis in a multiorgan transplant unit involving adult patients. Although no fingerprinting or subtyping of the virus was performed we assume the child was the primary source. In transplant recipients presenting with diarrhea RV infection should be considered.

Left atrial thrombus mistaken as a tumor after heart transplantation.

The occurrence of neoplastic malignancy due to chronic immunosuppression in heart transplant recipients is a well-known threat. Continuous check-ups are therefore mandatory in this patient group. We describe the case of a 58-year-old man transplanted for dilated cardiomyopathy. During regular diagnostic check-up, a solid mass in the left atrium was discovered on the transesophageal echocardiogram. Since the mass became progressively larger over three years and showed features of neither myxoma nor thrombus, a cardiac sarcoma was suspected. A secondary diagnostic magnetic resonance tomography (MRT) investigation was contraindicated due to an implanted pacemaker. Intraoperatively, the mass proved to be an organized thrombus. Surgery had to be performed without an established accurate diagnosis due to a suspected malignancy in chronically immunosuppressed patients.