What is this fleshy lump growing under my armpit?

A fleshy lump under the arm may result from skin hyperplasia—commonly referred to as a skin tag or soft fibroma. Such lumps are typically benign. Alternatively, it could be a lipoma arising from the subcutaneous fat layer; these are usually painless and grow slowly, often requiring no specific treatment. However, the lump might also indicate lymph node infection or metastatic cancer, necessitating prompt medical evaluation at a hospital to confirm the diagnosis and initiate appropriate treatment.