Synonyms: raccoon eyes, raccoon sign, panda sign, periorbital ecchymosis or periorbital hematoma

The clinical triad comprising of unilateral or bilateral progressive proptosis, periorbital ecchymosis, and edema is called raccoon sign.[1]

The pooling of blood around the eyes is most commonly associated with fractures of the anterior cranial fossa. This finding is typically not present during the initial evaluation and delays by 1 to 3 days.[2] If bilateral, this finding is highly predictive of a basilar skull fracture. Classically, the tarsal plate will be spared. Further extravasation of the blood beyond the periorbital region is limited owing to the orbital septum inserting into the tarsal plate.[3]

When a skull base fracture is present, the raccoon sign is present in 50 to 60% of cases.[4] This sign can be easily identified and is usually associated with anterior skull base fractures, especially of the frontal bone with an associated epidural hematoma. Thin-cuts computed tomogram of the skull (less than 5 mm) is needed to identify the fracture in some cases.

If the raccoon sign is present in a trauma victim, one should be aware of the following associated injuries or complications:

1. Cerebrospinal fluid (CSF) rhinorrhea
2. Injury to eyeballs
3. Injury to cranial nerves I, II, III, IV, VI
4. Intracranial misplacement of the nasogastric or nasotracheal tube
5. Diffuse axonal injury
6. Insult to the hypothalamic-pituitary axis (HPA) leading to endocrinopathies
7. Maxillofacial injuries
8. Cervical spine injury
9. Meningitis, at a later stage

Although commonly associated with skull base fracture, raccoon sign may also present in a variety of other conditions (limited to case reports), which include:

1. Traumatic: unilateral and bilateral orbital fractures[4][5][6][7][8][9][10]:
   1. Minor periorbital trauma, like the plucking of eyebrows
   2. Non-accidental injuries
   3. Thoracic trauma and crush injuries
   4. Following vigorous sneezing, coughing or vomiting - probably due to periorbital venous hemorrhage
   5. Posttraumatic orbital emphysema (due to fracture of orbital wall and entrapment of air from paranasal sinuses)
2. Vascular[11][12][13][14][15][16][17][18]:
   1. Subarachnoid hemorrhage (SAH) from ophthalmic artery aneurysm
   2. Sinus thrombosis - dural, superior sagittal sinus, and cavernous sinus thrombosis
   3. Giant cell arteritis
   4. Trigeminal autonomic cephalalgia
   5. Benign intracranial hypertension
   6. Acute migraine (due to vasodilation and release of vasoactive substances including heparin)
3. Infectious[19][20][21][20][19]:
   1. Severe pediatric adenovirus infection
   2. Periorbital leukoderma
   3. Frontal sinus mucocele
4. Immune-mediated[22][23][24][25]:
   1. The neonatal lupus erythematosus (vasculitis may lead to facial and periorbital purplish-red plaques)
   2. Chronic atypical neutrophilic dermatosis with lipodystrophy and elevated temperature (CANDLE) syndrome (neutrophilia and skin lesions containing mature neutrophils may also cause raccoon eyes appearance due to periorbital erythematous edema; due to a predilection to involve periorbital skin)
   3. Lichen planus pigmentosus (hyperpigmentation due to pigment incontinence)
   4. Sweet syndrome or acute febrile neutrophilic dermatosis is a skin disease characterized by the sudden onset of fever, an elevated white blood cell count, and tender, red, well-demarcated papules, and plaques that show dense infiltrates by neutrophil granulocytes on histologic examination.
      • Raccoon sign in this condition is due to secondary vascular damage caused by prolonged exposure to matrix metalloproteinases.
      • Toxic products of neutrophils in the infiltrate may be responsible for vascular damage leading to erythrocyte extravasation.
5. Metabolic[26][27]:
   1. Amyloidosis (most commonly, light chain (AL) type) – due to increased vascular fragility as a result of amyloid deposition - this is one of the most common causes of raccoon eyes other than trauma; the finding presents in about one-fifth of patients with AL amyloidosis
   2. Myxedema
6. Malignancies[28][29][30][1][31][32][33][34]:
   1. Hematological malignancies: blastic plasmacytoid dendritic cell neoplasm, lymphoblastic lymphoma, acute myeloid leukemia
   2. Metastatic neuroblastoma (secondary to tumoral obstruction of the palpebral vessels): neuroblastoma can present as periorbital ecchymosis in 5.4% of cases
   3. Orbital metastasis of solid malignancies
   4. Kaposi sarcoma
   5. Multiple myelomas: Infiltration of amyloid proteins in the capillaries lead to increased fragility, which can burst under minor stress, resulting in raccoon sign - usually, such an ecchymosis is painful in multiple myeloma.
7. Genetic:
   1. Hemophilia
8. Iatrogenic (perioperative raccoon eyes)[35][36][37][38]:
   1. Usually associated with systemic amyloidosis of AL type
   2. Post-rhinoplasty (due to a bleeding disorder)
   3. Post-endoscopic retrograde cholangiopancreatography (ERCP) (prone positioning, consumption of steroid and Valsalva maneuver might cause increased venous pressure which in turn lead to the rupture of fragile vessels in the orbit of an elderly patient)

If a nurse encounters a patient with a raccoon sign, he or she should immediately ask about a history of trauma, CSF rhinorrhea, and difficulty in vision. One should avoid inserting a nasogastric tube in such patients as intracranial placement of the tube may occur accidentally. It is better to place the orogastric tube instead, if necessary.

The periorbital ecchymosis perse resolves within 2 to 3 weeks.