Funtabulously Frivolous Friday Five 172

An owl

Spinal metastases are common in malignant tumors. Up to 80% of cancer patients have spinal metastasis at autopsy and the spine is the principle site for bony metastasis (50%).

Plain XR of the spine are a valuable and readily available initial imaging study. Plain x-ray film findings include pedicle erosion, paraspinal soft-tissue shadows, wedge compression, and pathological fracture–dislocation. One of the first signs of vertebral metastases is disappearance of the pedicle on the AP X-ray. This is known as the winking owl sign.

Anteroposterior and lateral radiographs demonstrate abnormal findings in up to 90% of patients with symptomatic spinal metastasis. Lytic lesions and vertebral collapse are common; however, both osteoblastic and sclerotic alterations also occur, especially with breast and prostatic metastasis. Intervertebral disc margins are invariably spared in metastatic tumor invasion, contrasting with the disc erosion commonly observed with infectious entities.

Jacobs, 2001

The winking owl sign is a reliable sign of osteolytic spinal metastases and is classically seen on AP radiographs of the thoracolumbar spine.  The loss of the normal pedicle contour and unilateral pedicle absence has been likened to that of a winking owl with the missing pedicle being the closed eye, the contralateral pedicle being the open eye and the spinous process being the beak.

In the image, the right pedicle of T8 (the left eye of T8) is not visible, suggesting destruction of the cortical bone of this pedicle.  This is classically associated with an osteolytic process of metastatic disease.

Differentials include, congenital absence, neurofibromatosis, radiation therapy, spinal metastases, intraspinal malignancies, TB or lymphoma

• Jacobs WB, Perrin RG. Evaluation and treatment of spinal metastases: an overview. Neurosurg Focus. 2001;11(6)
• Cadogan M. Winking owl sign. LITFL

Rat’s tail and Bird’s Beak

This a sign representing the tapering of the inferior oesophagus during a barium swallow.

The cobra head sign (or spring onion sign)

It refers to the dilatation of the distal ureter surrounded by a thin lucent line. It indicates an uncomplicated ureterocele.

If there is any irregularity or loss of definition this should raise concerns for a pseudoureterocele.

• Cobra head sign – intravenous urogram. Radiopedia
• Ultrasound Case 073. LITFL
• Tirman PA, Dyer RB. The cobra head sign. Abdom Imaging. 2015;40 (3): 609-10. 

Stag’s antler sign

Upper lobe pulmonary venous diversion (cephalisation). Prominence of the pulmonary veins are said to resemble stag’s antlers, the earliest sign of pulmonary oedema (pulmonary venous hypertension)

• Stag’s antler sign (lungs) Radiopedia

Butterflies

Butterfly fragments are large triangular fragments commonly seen in comminuted long bone fractures.