Heralding Extramedullary Blast Crisis: Horner's Syndrome with Brachial Plexopathy in a Patient with Chronic Myelogenous Leukemia

Abstract

Chronic myelogenous leukemia (CML) blast crisis is an ominous clinical event that is challenging to treat. This can develop at extramedullary sites rarely and is defined as the infiltration of blasts outside the bone marrow irrespective of proliferation of blasts within the bone marrow. We aim to report an unusual clinical presentation characterized by Horner's syndrome, ipsilateral arm weakness, and cervical lymphadenopathy as the first signs of extramedullary blast crisis in a CML patient. To the best of our knowledge, the extramedullary locations involving the brachial plexus along with cervicothoracic paraspinal chloroma have not been previously reported in the literature.

Figure 1

Patient with left Horner's syndrome: normal right eye (a) and external examination in comparison to left eye (b) with ptosis, miosis, and enophthalmos.

Figure 2

Magnetic Resonance Imaging (MRI) of the cervical spine and brachial plexus at cervical-thoracic levels: T2-weighted images with left paraspinal soft tissue mass and brachial plexus infiltration in sagittal (a), coronal (b), and axial (c) views and intraspinal extension (d).

Figure 3

Computed Tomography (CT) scan of soft tissue neck demonstrating right occipital (solid arrow) and right jugulomandibular (dotted arrow) cervical lymphadenopathies.

Figure 4

Histopathological analysis. (a) Low magnification view with effacement of lymph node architecture. (b) High magnification view with numerous immature cells (blasts). (c) A proportion of the immature cells are positive for myeloperoxidase by immunohistochemistry. (d) A proportion of the immature cells are positive for CD117 by immunohistochemistry.