Marco, Loredana De

Mastocytosis is a rare and heterogeneous group of disorders that may be limited to the skin and even spontaneously regress or may have a systemic presentation with multi-organ involvement and poor outcome. Among the extracutaneous sites, gastrointestinal tract is often affected, but nonspecific clinical manifestations combined with subtle histological findings of the disease makes the diagnosis of gastrointestinal mastocytosis rather hard. In absence of a high index of suspicion, gastrointestinal involvement is easily overlooked. We report a challenging case of systemic mastocytosis presenting with isolated gastrointestinal manifestations without skin involvement, in which the diagnosis was missed at first evaluation of intestinal biopsies.

AimErdheim–Chester disease represents a clonal systemic proliferation of histiocytes. Bone is the most common site of involvement, although almost any organ, including the lungs, can be affected.Methods and resultsThe diagnosis of Erdheim–Chester disease can be difficult, owing to its rarity and protean presentation. Correlation between clinical, radiological and histological findings is mandatory for identification of the disease. Foamy histiocytes, lacking Langerhans cell markers, represent the typical histological findings, although their absence does not rule out Erdheim–Chester disease. Identification of BRAF mutation can be helpful in making the diagnosis, and allows for the development and application of targeted therapies in this setting.ConclusionsHerein, we describe two cases presenting with lung involvement and vertebral lesions, lacking the more typical long‐bone involvement. One case histologically mimicked Rosai–Dorfman disease. However, both cases harboured the pathognomonic BRAFV600E mutation.