Patient with known and treated bronchial carcinoid who presented with increasing pain involving the right upper thigh.
The patient is a 71-year-old male with known and treated bronchial carcinoid who presented with increasing pain involving the right upper thigh. Radiography (Fig. 1a) was obtained, followed by lower extremity MR imaging (Figs. 1b-1c).
Radiography of the proximal right femur showed an ill-defined area of increased density in the medullary space, without apparent cortical or periosteal involvement. MR imaging showed a low T1 signal and high T2 signal mass with well-defined margins and periosteal reaction indicating an aggressive process. The clinical suspicion for metastatic carcinoid was high and confirmed at biopsy (Fig. 1d).
Carcinoid is a neuroendocrine tumor that arises from enterochromaffin cells of the alimentary tract. This malignancy is classified based upon its embryonic origin, and may involve the foregut, lungs, bronchi, midgut, and hindgut [1]. Histologically, carcinoid tumor cells appear in clusters surrounded by fibrous strands, with large, uniform, hyperchromatic nuclei and eosinophilic cytoplasm [2]. Bronchial and gastrointestinal carcinoids are histologically distinguished by the presence of argentaffin and argyrophil granules, which are present in gastrointestinal carcinoid and rarely seen in bronchial carcinoid [3]. Histologic features do not determine malignant potential [4].
The majority of patients with carcinoid tumors are asymptomatic and diagnosed incidentally. Symptoms are usually related to the location of the tumor, with the exception being patients that develop carcinoid syndrome. The syndrome occurs in a small number of patients, with 90% of cases demonstrating metastatic involvement of the liver. These patients classically present with systemic effects, which include skin flushing, diarrhea, and cyanosis, caused by the vasoactive amines secreted by carcinoid cells. Approximately 10% of carcinoids metastasize, which may occur as late as 20 years following initial resection of the primary tumor [3].
Metastases to bone are more frequently associated with bronchial as opposed to gastrointestinal carcinoid. Bone metastases typically involve the axial skeleton and are usually osteoblastic in nature. On radiographs, osteoblastic lesions of carcinoid metastases are indistinguishable from prostatic metastases and chronic sclerosing osteomyelitis [1]. Solitary sclerotic lesions with periosteal reaction in a sunburst pattern, an appearance similar to osteosarcoma, have been reported in carcinoid metastases [3]. Osteolytic lesions may also be seen, but in these cases the carcinoid is more likely to be of gastrointestinal origin [2]. Skeletal scintigraphy typically shows increased radiopharmaceutical uptake.
The treatment of choice for primary bronchial carcinoid is resection, which offers an excellent prognosis due to the slow growth of carcinoid tumors. Bony metastases are most commonly treated with external radiation therapy; the primary goal is symptom relief. Metastatic disease is generally indolent, with some patient survival reports showing survival greater than 10 years from the initial diagnosis of metastatic disease [1].
Carcinoid Tumor Metastatic to the Femur
On the X-ray plain film of the proximal right femur, thickening and sclerosis of the local bone cortex can be observed, presenting as a relatively localized region of increased sclerotic density. On the coronal and axial MRI sequences of the proximal right femur, an abnormal bone signal is seen. On T1WI, relatively low or isointense signals are noted, while on T2WI (or STIR) the signals appear relatively high, with well-defined margins. No obvious soft tissue mass formation or significant cortical destruction is observed. There are no signs of pathological fracture, although the local bony structure is clearly altered, suggesting possible metastatic lesions or other sclerotic bone lesions.
Given the patient’s previous diagnosis and treatment history for “bronchial carcinoid” and the imaging findings consistent with typical sclerotic metastases from carcinoid tumors, the most likely diagnosis is bone metastasis from a bronchial carcinoid.
Considering the patient’s advanced age (71 years old), established history of bronchial carcinoid treated in the past, progressive right thigh pain, and imaging revealing a sclerotic lesion, the most probable final diagnosis is metastasis from bronchial carcinoid to the proximal right femur. If clinically indicated, further assessment by bone biopsy or PET-CT can be performed to confirm the diagnosis and determine the extent of disease.
Treatment Strategies:
Rehabilitation/Exercise Prescription Recommendations (FITT-VP Principle):
During rehabilitation, the stability of the bone lesions should be periodically monitored. If there are significant changes in pain or function, consult the specialist promptly to adjust the exercise program.
Disclaimer: This report is provided for reference purposes only and does not replace in-person consultation or professional medical advice. To determine and implement a specific treatment plan, please consult with relevant clinical specialists to receive individualized guidance.
Carcinoid Tumor Metastatic to the Femur
