Background and objective
Idiopathic mast cell activation syndrome (IMCAS) presents with a wide range of mutisystem  presentations secondary to release of mast cell mediators without accumulation of mast cells. A rare and often missed cause of abdominal pain, its other symptoms may include dermatological, gastrointestinal, respiratory, cardiovascular, neuropsychiatric and even unexplained anaphylaxis. It thus may present with episodic flushing lasting from minutes to hours which may be induced by exercise, alcohol, stress and fluctuations in temperature., in addition to intermittent abdominal pain, heartburn, nausea, vomiting, diarrhea, and abdominal cramping. The pain associated can be severe, scoring 9/10 on NRS. Respiratory effects include bronchoconstriction and angioedema of the upper airways. Cardiovascular signs include hypotension with resultant syncope. Mild cognitive effects with headaches, fatigue and lack of concentration are common.  There may be an associated increase in mast cell tryptase levels following episodes helping diagnosis. The exact pathophysiology in IMCAS is unknown, but presumed to be  G-Protein receptor mediated modulation of chloride current. Antihistamines, cromolyn sodium and antileukotriene agents are commonly used in  symptom management. We present the case of a patient diagnosed with IMACS  complaining of chronic abdominal pain which was controlled with mast cell stabilizer sodium cromoglycate . 
Methods
A 27 year old female presented to the Gastroenterology and pain  clinics with abdomino-pelvic pain and altered bowel habits. The pain was intermittent, dull, aching and burning. Severity was 9-10/10 on NRS. Her sleep was affected as a result. Initially presumed to be Inflammatory bowel disease (IBD), this was refuted by investigations. Various medications were tried including Balsalazide, Fexofenadine, Cyclosporine, and Mesalazine Enema prn. There was some benefit with symptom management, however <30% relief in pain symptoms. Other medications prescribed include salbutamol and beclomethasone inhaler, Fluoxetine and the oral contraceptive pill. 
Eventually, after review by various specialities ( including dermatology, respiratory, haematology and gastroenterology)  a diagnosis of IMACS  was reached based on weekly episodes of lip, tongue, throat and eye swelling lasting 30 minutes to 2 hours. Hence, She was started on a sodium cromoglycate trial.
Results
There  was a significant reduction in pain severity on NRS  from 9/10 to 1 /10.
Conclusion
IMACS is an increasingly recognied cause of abdominal pain. These patients may benefit from trial of sodium cromoglycate. Further research is needed.
References
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Gerhard J Molderings, Stefan Brettner, Jürgen Homann, Lawrence B Afrin. Mast cell activation disease: a concise practical  guide for diagnostic workup and therapeutic  options . J Hematol Oncol. 2011; 4: 10.
Molderings g, haenisch b, brettner s, homann j, menzen m, dumoulin fl, panse j, butterfield j, afrin lb. Pharmacological treatment options for mast cell activation diseasPharmacological treatment options for mast cell activation disease. Naunyn-Schmiedeberg's Arch Pharmacol (2016) 389:671–694 
Wirz s, molderings g j.  Practical Guide for Treatment of Pain in Patients with Systemic Mast Cell Activation Disease. Pain physician. 2017;20(6):E849-E861

SODIUM CROMOGLYCATE IN THE TREATMENT OF ABDOMINAL PAIN IN A PATIENT WITH MAST CELL ACTIVATION SYNDROME