A 50-year-old post-menopausal female presented to the orthopaedic department with an inability to bear weight on her right leg following a trivial fall. Her past medical history was significant for a neck swelling for the last 20 years which was being treated by indigenous ayurvedic medicines. Otherwise, her medical, gynaecological and surgical history was unremarkable.
Radiograph of the right thigh revealed a lytic lesion in the subtrochanteric region with a displaced pathological fracture. Bone fragments were seen in the adjacent soft tissue. The mineralisation of skeleton appeared normal for age and sex [Figure 1a].
Screening chest radiograph revealed a soft tissue density lesion compressing and displacing the trachea towards the right. Bilateral lung fields and cardiac shadow were unremarkable [Figure 1b].
Contrast-enhanced CT of chest and abdomen was performed for identification of a primary lesion and metastatic workup which demonstrated a heterogeneously enhancing mass completely replacing both lobes of thyroid with few chunky calcifications, displacing the oesophagus and trachea to right, focally abutting the left CCA & brachiocephalic vein with its luminal attenuation. No significant lymphadenopathy was seen. Sections of the lung demonstrated few randomly distributed soft tissue nodules on a background of chronic infective changes. Lower sections of pelvis also demonstrated the pathological fracture with soft tissue within [Figure 2].
Background
Papillary carcinoma of thyroid is the most common thyroid malignancy followed by follicular carcinoma. A major difference between the two is higher hematogenous spread of malignancy in the latter [1]. In a female patient presenting with pathological fracture, breast carcinoma tops the list of differential diagnosis followed by thyroid malignancies [2].
Clinical Perspective
The usual clinical presentation of differentiated thyroid cancer is a thyroid mass but presentation as a pathological fracture may be seen in up to 38-62% cases [3,4]. The axial skeleton accounts for the more common site of bone metastasis with isolated appendicular skeletal metastasis being a rarer occurrence. Presentation with pathological fracture warrants imaging for identifying the primary lesion as well as for metastatic workup. Considering the age and sex of our patient, breast and thyroid malignancy were the top two differentials which were assessed by clinical examination and then imaging.
Imaging Perspective
Awareness about features of a pathological fracture is necessary to point the clinician in the correct direction and fasten the diagnostic process of already advanced malignancy. Presence of a lytic lesion, a horizontal fracture line and enhancing soft tissue within the broken cortex on cross-section imaging are the pointers to a metastatic pathological fracture.
Diagnosis relies on biopsy from the lesion which can be taken either during fixation or under image guidance.
In our case, the thyroid lesion appeared aggressive on imaging with no evidence of mass in either breast and thus, was the imaging diagnosis for the possible primary lesion which was then confirmed following a bone biopsy from the fracture site and FNAC from the thyroid lesion.
Outcome
Radiotherapy with surgical fixation of the pathological fracture and concurrent bisphosphonate therapy was offered to the patient.
Take-Home Message / Teaching Points
Vigilance about features of a pathological fracture is important along with awareness about the most prevalent possible primary lesions presenting as bone metastasis to begin a thorough search in the correct direction and reach the diagnosis for early intervention and treatment.
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Follicular carcinoma of thyroid presenting as a pathological fracture.
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On the plain film of the right proximal femur (see attached X-ray images), a prominent radiolucent area with irregular margins suggests a lytic lesion. A nearly horizontal fracture line can be observed (spanning the lesion), accompanied by thickening of the surrounding soft tissue shadow, consistent with the morphological characteristics of a pathological fracture. The pelvis and the contralateral femur appear relatively normal, with only mild degenerative changes.
On the chest X-ray, a widened shadow is visible adjacent to the trachea in the neck region. Further CT examination (cervical and thoracic levels) reveals a space-occupying lesion in the right lobe of the thyroid gland with indistinct borders, showing uneven enhancement in some areas and extending longitudinally into the neck and upper mediastinum. Lung reconstruction images indicate multiple small nodular lesions, some presenting as round radiolucent areas, raising high suspicion of metastatic lesions. Considering the patient’s long-standing history of thyroid enlargement, the thyroid lesion here shows malignant features.
1. Breast Cancer with Bone Metastasis: In postmenopausal women with bone destruction and pathological fractures, breast cancer is a common consideration. However, no definitive breast lesions or significant axillary lymph node metastases were found in the examinations, reducing its likelihood.
2. Thyroid Cancer with Bone Metastasis: The patient has a 20-year history of a neck mass, and imaging suggests a localized thyroid lesion with evidence of lung and bone metastases. Thyroid cancer, especially follicular or papillary carcinoma, can present with distant bone and lung metastases at advanced stages, making it a highly suspicious diagnosis.
3. Other Malignant Tumors with Bone Metastasis: These may include lung cancer, renal cancer, etc. However, based on the current imaging and clinical information, the thyroid lesion appears more relevant, and the chest CT mainly indicates multiple pulmonary metastases. The primary lesion is most likely in the thyroid.
Considering the patient’s long-term history of thyroid enlargement, pathological fracture seen on bone imaging, thyroid lesion on neck/thoracic imaging, and multiple bone and lung metastases, together with subsequent pathological biopsies (bone lesion biopsy and fine-needle aspiration biopsy of the thyroid), the most likely diagnosis is “Papillary Thyroid Carcinoma with Multiple Bone Metastases.”
• Surgery and Local Stabilization: Since the patient has a pathological fracture, consider internal fixation to stabilize the bone structure before radiotherapy or (if conditions permit) radionuclide therapy, to alleviate pain and improve mobility. • Systemic Treatment: For patients with thyroid cancer and bone metastases, options may include surgical resection or partial resection of the thyroid tumor (depending on the extent of the lesion and patient condition), combined with radioactive iodine therapy or external beam radiotherapy. The use of bisphosphonates or osteoclast inhibitors can slow bone destruction and reduce bone pain. • Radiotherapy: Localized radiotherapy can help control the lesion, relieve pain, and promote fracture healing or stability. • Medication: After evaluating endocrine function, based on the specific pathological type and differentiation degree, targeted therapy or TSH suppression therapy can be considered as appropriate.
Once the fracture has been internally stabilized or is largely stable, an individualized rehabilitation protocol should be implemented:
Throughout rehabilitation, dynamically assess the patient’s pain levels, fracture healing progress, and response to cancer treatment. If any significant discomfort or changes in condition arise, consult specialist physicians promptly to adjust the plan.
This report is based on the current imaging and clinical data for reference only and does not replace in-person consultation or medical advice from professional physicians. For any diagnostic or therapeutic adjustments, please consult specialists in the relevant fields for more accurate, personalized guidance.
Follicular carcinoma of thyroid presenting as a pathological fracture.
