Acute radiotherapy toxicity in 57 dogs with gross and microscopic mast cell tumours.

Mast cell tumours (MCTs) are commonly treated with radiation therapy, most often in a microscopic disease setting. Poorer outcomes are expected in patients with gross disease, and irradiation of gross disease may be associated with greater toxicity. The aim of this study was to compare acute radiation adverse events (AE) in dogs with gross and microscopic MCTs receiving radiotherapy. Fifty-seven dogs were included, 28 with gross disease and 29 with microscopic. In order to assess mucosal and skin toxicity, patients were assigned to 2 groups: head (29 patients, 14 patients with gross and 15 microscopic) and other sites (28 patients, 14 each). All were treated with external beam radiotherapy, and toxicity assessed at the end of treatment and 10 to 14 days later (first recheck). All patients developed some acute radiation toxicity by the end of the course. However, there was no difference in the severity of toxicity between gross and microscopic disease in either site group at either time point. The only variable associated with an increased frequency of grade 2 or 3 toxicity at the first recheck was the use of prednisolone prior to radiotherapy (P = .05). No other factors were identified which were associated with increased toxicity. For the head group, the site of highest grade toxicity was mucosa or, if included in the field, nasal planum, which was often more severely affected than the mucosa. No significant late toxicity was identified. Two dogs developed acute haematemesis during the radiotherapy course, but both completed the course without further events.

Management of poorly controlled indolent systemic mastocytosis using narrowband UVB phototherapy.

The mastocytoses comprise a group of proliferative stem cell disorders defined by the abnormal accumulation of mast cells (MCs) in the skin or other body tissues including the bone marrow, gastrointestinal tract, and liver. Systemic mastocytosis is defined by the presence of one major and one minor criterion or 3 minor criteria delineated by the World Health Organization (WHO). We present the case of a 57-year-old woman with a 10-year history of red-brown pruritic maculopapular lesions on the upper and lower extremities and trunk who was originally diagnosed with cutaneous mastocytosis. Symptoms had been adequately controlled with a combination of topical corticosteroids and antihistamines. After 9 years of controlled disease, the patient presented with increasingly severe breakthrough pruritus and new skin lesions on the head and neck. Further workup included bone marrow biopsy, which demonstrated dense mastocyte infiltrates without evidence of functional impairment, and elevated serum tryptase levels. Narrowband UVB (NB-UVB) phototherapy was initiated, and after 20 treatments the patient reported a marked decrease in symptoms. This case provides evidence of the efficacy of NB-UVB phototherapy in managing patients with long-standing indolent systemic mastocytosis (ISM) who have stopped responding adequately to topical corticosteroids and antihistamines.

Indolent systemic mastocytosis treated with narrow-band UVB phototherapy: study of five cases.

BACKGROUND: Mastocytoses represent a heterogeneous group of stem cell disorders marked by an abnormal hyperplasia and accumulation of mast cells in one or more tissues, including bone marrow, gastrointestinal tract, liver, spleen, lymph nodes and skin. Indolent systemic mastocytosis (ISM) is characterized by red-brownish and pruriginous maculopapular lesions, a bone marrow infiltration without functional impairment and an indolent clinical course with a good prognosis. In particular, the most common cutaneous symptoms are urticarial rash and mild-to-high pruritus. OBJECTIVES: This study analyses the clinical outcome of patients affected by ISM with prevalent pruriginous cutaneous symptoms and a scarce response to anti-histamines treated using narrowband ultraviolet B (NB-UVB) phototherapy. METHODS: Narrowband ultraviolet B phototherapy was administered in a UV-irradiation cabin equipped with fluorescent UVB lamps with a peak emission at 311-313 nm. The perception of pruritus severity was assessed using the Visual Analogue Scale (VAS) before starting the treatment and at each control. RESULTS: A complete remission of the cutaneous lesions and pruritus was documented in all patients after a median of 40.3 UV treatments and a median cumulative dose of 51.4 J/cm(2), with a lasting remission over a 6-month follow-up. The median VAS score at the beginning of the treatment was 86.6 (SD=6.64), whereas it decreased to 6.66 (SD=3.75) after 3 months of therapy. CONCLUSIONS: Our work provides evidence that NB-UVB phototherapy is useful for the treatment of the cutaneous symptoms and pruritus in ISM.

[Treatment of systemic mastocytosis]. / Traitement des mastocytoses systémiques.

BACKGROUND: Systemic mastocytosis is a rare disease, characterized by mast cells proliferation in various organs. Two types of clinical manifestations can be distinguished: those related to mast cells mediators release and those related to tumoral proliferation involving different organs, these later defining aggressive systemic mastocytosis. Until recently, treatment was mainly symptomatic, without anti tumoral effect. RECENT FACTS: These last years, advances have been made in the understanding of the disease with the discovery of the c-kit oncogene mutation and the approach of the disease as a myeloproliferative disorder. PERSPECTIVES: Based on experiences acquired in the treatment of this kind of disorders, evaluation of new therapeutics, such as cladribine or combination of interferon-alpha and cytarabine is in progress. At least, tyrosine kinase inhibitors, a new family of molecules, are able of inhibiting some types of the mutated c-kit protein and one of them, imatinib mesylate, has shown a great efficacy in the treatment of gastro intestinal stromal tumors (GIST) which also involves the c-kit mutation. By analogy, treatment of patients with c-kit susceptible mutation might be treated with this molecule.