P3C063: Not Getting the GIST: An Adolescent Female with Iron Deficiency Anemia

Introduction: Iron deficiency anemia in an adolescent female is usually assumed secondary to heavy menstrual bleeding due to its high prevalence in this population. We present a case of an adolescent female patient treated for severe iron deficiency anemia who was ultimately diagnosed with a gastrointestinal stromal tumor (GIST).

Case Description: A healthy 16-year-old female presents for evaluation for fatigue and pallor. Labs showed Hgb 6.2 and ferritin 3 consistent with profound iron deficiency anemia (IDA). She had no easy bleeding, bloody or dark stools, or abdominal pain. She had no family history of bleeding disorders. She noted menarche at age 12 and has regular monthly menstrual cycles. They last for 6 days with 3 days of heavier bleeding in which she changes her tampons every 2-hours and she thinks they are typically soaked through. Her IDA was therefore felt secondary to menorrhagia and referred to gynecology for further evaluation, however was subsequently lost to follow up.

She returned to the emergency department 10 months later with syncope alongside a new left frontal headache. Her Hgb returned at 5.1. She felt her menorrhagia had seemed to be improved over the last few months, but admitted to nonadherence to the iron pills. Head imaging showed venous sinus thrombosis. Given her profound anemia with improved menorrhagia and new thrombosis, the differential diagnosis was broadened to include underlying hypercoagulable state or hemolytic anemia. Workup for genetic thrombophilia and hemolytic anemia all returned within normal limits. Family elected to discharge home and obtain further workup as an outpatient including fecal hemoccult after the patient’s symptoms were improved following symptomatic management.

The patient returned three days later with another episode of syncope, fatigue, and pallor, and was found to have Hgb 4.5. Fecal hemoccult returned positive and CT abdomen/pelvis with contrast was obtained, which showed a multilobulated gastric mass. She underwent EGD-guided biopsy with pathology returning consistent with a gastrointestinal stromal tumor.

Discussion: The differential diagnosis for IDA in an adolescent female is often prematurely closed due to the association with menorrhagia and perceived difficulty in quantifying their bleeding, often further worsened by non-adherence to treatment. In older adults, new IDA is usually treated as bleeding secondary to malignancy until proven otherwise. Gastrointestinal stromal tumors (GISTs) are rare neoplasms originating from the interstitial cells of Cajal most commonly affecting the stomach and older adults with a median age of diagnosis in the late 60s. GISTs may be rarely diagnosed in younger patients with indolent presentation and a notable association with neurofibromatosis 1.

Conclusion: This case highlights a number of common diagnostic errors such as premature closure and anchoring that often affect adolescents disproportionately. Thorough evaluation and follow up should be performed in patients of all ages with iron deficiency anemia.