Technetium-99m methylene diphosphonate uptake in the brachialis muscle hematoma in a patient with prostate cancer and coagulation disorder mimicking bone metastasis evaluated by single-photon emission tomography-computed tomography/computed tomography.

We report a case of 79-year-old male with prostate cancer and coagulation disorder presented with left shoulder pain. He underwent bone scintigraphy to rule out metastasis, which showed intense foci of tracer activity in the left axilla. Hybrid single-photon emission tomography-computed tomography (SPECT/CT) of the shoulder region localized tracer uptake to the left brachialis muscle hematoma.

INTRODUCTION

Extraosseous soft-tissue uptake of technetium-99m methylene diphosphonate (Tc-99m MDP) can occur in number of occasions. Cancer patients those undergoing bone scintigraphy will have abnormal uptake, which should be differentiated from benign and metastasis in a planar bone scan. Hematoma showing MDP uptake has been reported in many cases.[12] single-photon emission tomography-computed tomography (SPECT/CT) help in localizing uptake to the muscle hematoma is not reported yet.

CASE REPORT

A 79-year-old man with prostate cancer and coagulation disorder was referred for a bone scan because of left shoulder pain. A bone scan was performed to assess for any skeletal involvement, especially in the shoulder. A total of 20 mCi (740 MBq) MDP was injected intravenously and imaging was performed 3 h later using a large field of view, dual headed gamma camera fitted with a low-energy, high-resolution collimator. Anterior whole-body images showed intense uptake in the left axilla [Figure 1]. SPECT CT of the chest [Figures 2 and 3] was performed to rule out whether the uptake is in the humerus, but it showed a hematoma in the left brachialis muscle, which he developed due to his coagulation disorder. A hematoma was confirmed on fine-needle aspiration and resolved spontaneously over the next 4-5 weeks. Follow-up bone scan carried out after 6 months showed resolution of uptake in the left axilla [Figure 4].

Figure 1

Technetium-99m methylene diphosphonate whole body bone scan showing increased uptake noted in the left axilla (arrow) and no other site of metastasis

Figure 2

Coronal computed tomography images showing hematoma in the left brachialis muscle

Figure 3

Fused coronal single-photon emission tomography-computed tomography images localises tracer uptake to the hematoma in the left brachialis muscle

Figure 4

Follow-up technetium-99m methylene diphosphonate whole body scan shows resolution of uptake in the left axilla after 6 months

DISCUSSION

Localization of bone imaging agents like Tc-99m MDP and Tc-99m hydroxymethylene diphosphonate has previously been described in abdominal and pelvic hematomas.[1] Extraosseous soft-tissue concentration of these radiotracers in the chest has also been reported in soft-tissue hematoma,[2] a benign intrapulmonary calcified focus,[3] squamous cell carcinoma of the pleura[4] and pulmonary alveolar microlithiasis.[5] Proposed mechanism leading to increased extraosseous Tc-99m MDP uptake include extracellular fluid expansion, enhanced regional vascularity and permeability, diminished lymphatic or venous removal from the affected area, and elevated tissue calcium concentration.[6] Tissue damage from inflammation, infection or physical trauma results in localized hyperemia, edema or calcium (and hemosiderin) deposition based on their pathophysiologic characteristics.[7] Extraosseous accumulation in the axilla has been reported rarely. Because of advent of SPECT CT, it is possible to localize exact site of tracer uptake and characterize the lesion to guide further management.[8] SPECT/CT localizing the uptake to the hematoma in the left brachialis muscle help in ruling out metastasis.