Anemia of Chronic Disease: This is the most likely diagnosis given the patient's history of Crohn's disease, an autoimmune condition that can lead to chronic inflammation. The elevated ferritin level (390) and low iron level (20) in the presence of a high TIBC (130) are indicative of anemia of chronic disease, where iron is sequestered and not available for erythropoiesis despite adequate stores.

Iron Deficiency Anemia: Although the ferritin level is elevated, which typically rules out iron deficiency anemia, the patient's Crohn's disease could lead to chronic blood loss or malabsorption, potentially contributing to iron deficiency. However, the high ferritin level makes this less likely.
Folate Deficiency Anemia: Given the patient's Crohn's disease, there could be malabsorption of folate, leading to deficiency. However, the mean corpuscular volume (MCV) is 84, which is within the normal range, making this diagnosis less likely.

Vitamin B12 Deficiency Anemia: This is crucial to consider in patients with Crohn's disease, especially if they have had portions of their ileum removed or have significant ileal disease, as the ileum is the primary site of vitamin B12 absorption. A deficiency in vitamin B12 can lead to neurological symptoms and severe anemia. Although the MCV is normal, this diagnosis should not be missed due to its potential for severe consequences if left untreated.

Sickle Cell Anemia: This is unlikely given the patient's age and the fact that sickle cell anemia typically presents in childhood. The peripheral smear description does not support this diagnosis.
Other rare causes of anemia might include autoimmune hemolytic anemia or other hemoglobinopathies, but these would be less likely given the patient's presentation and the information provided from the laboratory studies.