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mastocytosis is a rare and heterogeneous disease characterized by the accumulation of abnormal mast cells in various tissues .
while cutaneous mastocytosis ( skin - localized form ) is the classical presentation in children and in pediatric cases tends to resolve spontaneously at puberty , systemic mastocytosis ( sm ) is more frequent in adults , is characterized by mast cells infiltration of extracutaneous organs ( e.g. bone marrow , liver , spleen , gastrointestinal tract , lymph nodes ) ; this form is progressive and has no tendency to regress .
both forms of mastocytosis might be considered myeloproliferative disorders . in most patients , sm is caused by mutations in the kit oncogene ( in particular the d816v mutation is present in > 80% of patients ) , which are responsible for c - kit receptor autophosphorylation , inducing differentiation , migration , accumulation of mast cells and their activation in tissues ; therefore , this receptor is now considered a therapeutic target using tyrosine kinase inhibitors .
the clinical manifestations of sm are related to the release of mast cells mediators ( e.g. facial flushing , urticaria , itching , diarrhea ) or to uncontrolled growth and infiltration of clonal mast cells in different organs ( e.g. hepatomegaly , liver fibrosis and rarely cirrhosis , splenomegaly , osteoporosis , malabsorption , pancreatic insufficiency ) ; most of the symptoms , though not being life - threatening , may induce a significant impairment of quality of life . nevertheless ,
when infiltration results in organ function impairment , the disease is considered aggressive and may decrease life expectancy [ 4 , 5 ] . up to 50% of patients with sm do not show classical skin lesions at presentation , and in these patients the diagnosis of sm can be difficult for years : according to the world health organization ( who ) diagnostic criteria , sm is diagnosed when the major and at least one minor criterion or three minor criteria are satisfied ( table 1 ) .
its signs and symptoms are divided into two groups : b symptoms (  borderline benign  be watchful ) and c symptoms (  consider cytoreductive therapy ) ( table 2 ) .
gastrointestinal symptoms are reported in up to 80% of patients with sm , are often chronic and represent a major source of morbidity : abdominal pain is the most common , while diarrhea is present in about 40% of patients with gastrointestinal symptoms and nausea and vomiting occur in approximately 30% .
a prevalence of 10% is estimated for gastrointestinal bleeding , in about 25% of cases caused by peptic ulcer disease . at present
there is no curative therapy for sm and the medical approach is aimed at symptomatic relief and improvement in terms of quality of life : sm patients should avoid mast cell degranulation triggers ( e.g. exposure to heat , cold , acute emotional stress , very strenuous exercise , alcohol ) , and commonly used symptomatic drugs are h1 and h2 histamine receptor blockers , ketotifen , cromolyn sodium and anti - leukotriene drugs , while cytoreductive regimens are indicated in sm with c symptoms [ 10 , 11 ] .
a 47-year - old woman , with a past medical history including turner 's syndrome with primary amenorrhea , polycystic kidney disease and previous appendectomy for acute appendicitis , was admitted to our hospital in 1995 for worsening fatigue , iron deficiency anemia and weight loss ( bmi of 16 at time of admission ) . according to endoscopic ( upper and lower gastrointestinal endoscopies ) , biochemical ( neutrophilic leukocytosis and elevation of phlogosis markers ) and radiologic ( abdominal ultrasonography scan , small bowel enema , barium enema ) findings
, she was discharged with a diagnosis of crohn 's disease involving the terminal ileum . oral treatment with tapering corticosteroid ( prednisone , starting with 50 mg / day and reducing by 5 mg every week ) was then started , but with poor clinical improvement .
two months after the end of steroid tapering , the patient underwent emergency right colectomy , resection of the terminal ileum ( 70 cm ) and ileocolic anastomosis for acute abdomen due to bowel obstruction .
the following scenario presented to the surgeons : relaxed and edematous preterminal ileum , stenotic and anelastic terminal ileum and wiry colon .
macroscopic pathological analysis revealed an ileal wall with regular thickness , expanded lumen and hyperemic mucosa and , 30 and 50 cm before the ileocecal valve , two salient features 1 cm in diameter covered with regular mucosa ; when cut , they appeared as whitish nodes located in the submucosa .
microscopic pathological examination showed substantial preservation of the architecture of the ileal wall and presence in the lamina propria of lymphocytes , plasma cells , eosinophils and a great number of partially degranulated mast cells ( 20/30 high - power fields ) , identified by immunohistochemical stains for tryptase .
many mast cells were found even in the mucosa , submucosa and tunica serosa ( fig .
1 ) , and the above - mentioned ileal whitish nodes resulted fibrotic and populated by fibroblasts , mast cells , plasma cells and lymphocytes .
giemsa and masson trichrome stainings , immunohistochemistry for actin , desmin , s100 protein , cd3 , cd20 and neurofilaments were performed ; according to histology , a diagnosis of intestinal involvement by sm was performed . during the following years the patient underwent regular follow - up
; she always remained asymptomatic for cutaneous or systemic symptoms and only occasional episodes of diarrhea were reported . in 2004 she underwent kidney transplantation for polycystic kidney disease and over the years she developed portal hypertension with esophageal varices in a context of caroli disease . at the last medical outpatient visit ( november 2010 )
the patient was in good condition and without any systemic symptoms ; she was just suffering from sporadic flares of diarrhea .
because of the peculiarity of the present case , a biopsy of the surgical specimen was recovered to perform immunohistochemistry analysis for cd117/c - kit ( fig .
2 ) and cd25 , obtaining the ultimate confirmation that she was fulfilling the who diagnostic criteria for sm .
gastrointestinal symptoms ( e.g. abdominal pain , diarrhea , nausea and vomiting , subocclusion ) are present in up to 80% of patients affected by sm and contribute to the morbidity of this disease .
symptoms are caused by the release of mast cell mediators or by tissue infiltration of clonal mast cells . according to the who criteria
, diagnosis is based on histological finding of atypical mast cells in tissue section , associated with mutation of c - kit or coexpression of cd2/cd25 or associated with persistent elevation of serum tryptase levels . in case of gastrointestinal involvement
the features of small bowel sm involvement can include thickened folds , nodular mucosa , edematous or scalloped folds and dilated bowel loops ; these findings are also typical for inflammatory bowel disease .
histological documentation in the small bowel can show , apart from the presence of a high number of atypical mast cells , increased plasma cell and eosinophil content in the lamina propria ; villous fluttering and atrophy can be present . in our patient , clinical presentation was atypical both for inflammatory bowel disease and sm ; the relatively advanced age of onset and non - response to steroid therapy could question the diagnosis of inflammatory disease .
the occurrence of acute abdomen with the need for emergency surgery allowed us , however , a deep and complete histological study of the surgical specimen and eventually led us to the diagnosis .
sm should always be considered in the differential diagnosis of bowel obstruction in adulthood , with or without significant previous cutaneous or gastrointestinal symptoms and even when a previous diagnosis of gastrointestinal disease other than sm has been made , especially if this is not entirely convincing .
we obtained the patient 's written informed consent to publish this case report and the publication has been approved by our institute 's committee on human research .
we disclose no sponsorship or funding arrangements relating to this research and no possible conflicts of interest .
systemic mastocytosis ( sm ) is a rare , heterogeneous and progressive disease , characterized by the accumulation of atypical mast cells in various organs , including the gastrointestinal tract . 
 gastrointestinal symptoms are present in up to 80% of patients with sm , the most common being abdominal pain , diarrhea , nausea and vomiting . up to 50% of patients with sm 
 do not have classical skin lesions at presentation , and in these patients the diagnosis of sm can be difficult for years . here 
 we report a case of sm that initially mimicked inflammatory bowel disease , although the patient showed poor response to steroid therapy . 
 the right diagnosis was made only on the surgical specimen obtained after emergency surgery for intestinal obstruction . 
 sm should therefore be considered in the diagnostic approach in patients with gastrointestinal symptoms not attributable to other pathologies and in cases of suspected inflammatory bowel disease with unusual course .