<aside>
Chipmunk facies is a clinical facial deformity classically seen in children with severe chronic hemolytic anemias—notably thalassemia major—characterized by prominent cheekbones, frontal bossing, depressed nasal bridge, and protrusion of upper jaw (maxillary hypertrophy), giving the appearance of a chipmunk’s puffed cheeks.
</aside>
| Mechanism | Details |
|---|---|
| Ineffective erythropoiesis | Drives hyperplasia of bone marrow in skull and facial bones |
| Marrow expansion | Leads to widening of diploic space, bone remodeling, and facial distortion |
| Maxillary overgrowth | Causes dental malocclusion and protruding upper teeth |
Most commonly associated conditions:
| Condition | Association |
|---|---|
| Beta-thalassemia major | Classical and most common cause |
| Sickle cell anemia | Less common, in chronic uncontrolled disease |
| Congenital dyserythropoietic anemia | Severe ineffective erythropoiesis |
| Other chronic anemias | Rarely if untreated and severe |
| Feature | Presentation |
|---|---|
| Frontal bossing | Prominent forehead |
| Protruding upper jaw | Maxillary hypertrophy |
| Malocclusion | Dental crowding, anterior open bite |
| Depressed nasal bridge | Flat midface profile |
| Puffy cheeks | Due to zygomatic bone prominence |
Classical ‘Chipmunk facies’ with frontal bossing, maxillary expansion, saddle nose and depressed cranial vault.
Singh A, Varma S β-Thalassaemia intermedia masquerading as β-thalassaemia major Case Reports 2014;2014:bcr2014207637.
| Modality | Imaging features |
|---|---|
| XR | • Frontal bossing: Expansion of frontal bones |
| • Hair‐on‐end appearance (skull): Vertical trabeculations in diploic space | |
| • Widened diploic space: From marrow hyperplasia | |
| CT | • Maxillary hypertrophy: Expansion of maxillary sinus walls |
| • Overgrowth of facial bones: Especially upper jaw |
(a) Chipmunk/rodent facies due to over-expansion of maxilla and mandible. (b and c) AP and lateral skull radiograph, elicits the protrusion of the maxilla and mandible. (b, c, and d) X-ray AP and lateral view and CT axial view showing widening of the diploic space and thinning of the inner and outer table with prominent secondary trabeculae.
Sen KK, Dubey R, Goyal M, Sharawat A. Imaging features in extramedullary hematopoiesis - A case series. Indian J Musculoskelet Radiol 2022;4:26-30.
Dental and orthodontic implications:
