Brief Answer: Cavity and metastasis are the amongst top 2 Detailed Answer: Hi.Thanks for writing on HCM. Mass generally means undefined tissue which can be tumour or abscess(collection of pus) or localized collection of fluid, hiatal hernia etc in the chest. Apart from this very common conditions which I come across in my clinic are cavity, metastasis, broken rib. Since these are quite common and they have to differentiated on certain parameters to make a proper diagnosis- Do you have any cough/breathlessness/weight loss/fever? Does it have regular/irregular border on X-ray? Does the X-ray show any shift of the wind pipe? Are the borders of the lung sharp? Are there any signs of fluid collection? Was there any history of lung infection in the past? Its difficult to make out these changes on X-ray(for a normal individual).I were to look for these and narrow down the possibilities and confirm by further by getting a CT scan. Hope this answers your query.

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