Keywords
low back pain - spinal diseases - neoplasm metastasis
Palavras-chave
dor lombar - doenças da coluna vertebral - metástase neoplásica
Introduction
Thyroid cancer is the most common tumor of the endocrine system.[1]
[2] It is usually divided in three major subtypes: papillary, follicular, and medullary.
The prognosis of patients with differentiated thyroid cancer is excellent and 10-year
survival is more than 90%.[1] Dissemination of thyroid cancer is primarily via regional lymph nodes and metastatic
pulmonary disease may develop, followed by bone involvement.[1]
Hürthle cell carcinoma is a rare variant of differentiated thyroid cancer and occasionally
generates distant metastases.[2]
[3]
[4] There are few reports of Hürthle cell carcinoma metastases to the vertebral column
and none with sacral involvement.[2]
[3]
[4] We report a unique case of Hürthle cell carcinoma metastasis to sacral spine presenting
with low back pain.
Case Description
We report a 48-year-old woman with a 2-year history of moderate low back pain irradiating
to posterior and medial left thigh, being initially alleviated with common analgesic
medication and physical therapy. After 1 year, she returned in use of paracetamol
and codeine with a milder sustained pain that increased at walking or long standing
up.
Her previous medical files were unremarkable. At that moment, she denied fever of
weight loss. She underwent new medical evaluation. Her physical examination, including
neurologic status, was normal. Because of long course of pain, she was submitted to
radiologic evaluation. Lumbar and sacral spine radiographs were initially of limited
help, but a lumbar and sacral tomography immediately revealed an osteolytic lesion
in the left S1 lamina, invading the vertebral canal. A magnetic resonance imaging
revealed a solitary hypointense T1 and T2 lesion on the left lamina of S1, which homogeneously
enhanced after endovenous gadolinium injection ([Fig. 1]). Among possible diagnosis, tumoral etiology was considered, and because of topography
and image, the main hypothesis included sacral chordoma, lymphoproliferative neoplasms,
and metastatic lesions. To determine the nature of lesion, the patient was submitted
to percutaneous biopsy guided by fluoroscopy, without any surgical complications.
Fig. 1 Radiologic evaluation. (A) A pelvic radiography with interference of gas in the colon. (B) Lumbar and sacral tomography revealing an osteolytic lesion in left S1 lamina, invading
vertebral canal. (C) Sagittal magnetic resonance imaging displaying a solitary hypointense T1 and T2
lesion on the left lamina of S1. (D) Axial magnetic resonance imaging on the left lamina of S1 homogeneously enhancing
after endovenous gadolinium injection.
Pathological findings were compatible with an oncocytic solid-glandular neoplasm.
Immunohistochemistry showed expression of tireoglobulin, CK7, and CK19, a pattern
compatible with Hürthle cell carcinoma of thyroid ([Fig. 2]). Immediately after diagnosis, she was submitted to thyroid ultrasound that revealed
a solitary, solid, lobulated, heterogeneous, predominantly hypoechoic with hyperechoic
foci nodule, with peripheral and central vascularization in the middle third of right
thyroid lobule. She was forwarded to Neck and Head Surgery Service for further approach.
Fig. 2 Pathological findings. (A) Histologic features of thyroid carcinoma in hematoxylin-eosin staining. (B) Immunohistochemistry revealing intense tireoglobulin staining, a typical finding
of Hürthle cell carcinoma.
Discussion
Thyroid cancer bone metastases frequently cause significant morbidity.[1]
[2] They may be present at the initial diagnosis in up to 50% of patients.[2] Spread of thyroid carcinoma to bone is more common in patients older than 45 years
and is characteristically symptomatic and multicentric.[2] In one series, the vertebrae, pelvis, ribs, and femur were respectively the most
common sites of metastases. Multiple lesions were present in 53% of the cases. The
overall 10-year survival rate from the time of diagnosis of thyroid cancer was 35%,
and from diagnosis of initial bone metastasis was 13%.[2]
Hürthle cell carcinoma is a rare variant of differentiated thyroid cancer characterized
by solid tumor nests and microfollicle formation, sometimes with abundant colloid
production and strong immunocytochemical reactivity for thyroglobulin.[3]
[4] Even in the presence of metastases, patients with Hürthle cell carcinoma usually
have a relatively good prognosis, being considered the most favorable histologic subtype
for survival.[3]
Few other reports disclosed Hürthle cell carcinoma as spinal metastasis, and none
with sacral involvement.[3]
[4]
[5] We highlight our case once it approaches a young woman presenting with atypical
symptomatology of low back pain as first clinical presentation of a solitary sacral
bone metastatic Hürthle cell carcinoma.
