Background: Myopericytoma is a rare, benign, slow-growing soft tissue tumor that developed from perivascular smooth muscle-like myoid cells (myopericytes) and shares features of both glomus and smooth muscle cells. It usually involves the skin and soft tissues and frequently affects the extremities. It is characterized by the concentric organization of these oval-to spindle-shaped myoid cells surrounding delicate vascular channels, displaying a characteristic concentric perivascular cell proliferation. Methods: A thirty-four-year-old male teacher from Port Sudan City presented with right posterior proximal forearm swelling for one week. The condition started one week prior to admission with posterior proximal forearm swelling, which rapidly increased in size, was not associated with pain, did not interfere with daily activity, and was not associated with fever or any other lumps in other sites of the body. On examination, there is right posterior proximal forearm swelling about 10×6 cm oval in shape, well demarcated, normal skin over it, no visible dilated veins, there is no hotness or tenderness, with a positive fluctuation and transillumination test, not attached to skin or underlying structure, and there is neither palpable thrill nor bruit. The lump was excised and was sent for histopathology. Result: The histopathology finding revealed features of a perivascular tumor consistent with myopericytoma. Conclusion and recommendations: Myopericytoma has a slow-growing course, unlike our case, which is rapidly growing over one week; this gives another manifestation of this tumor which may help to understand its etiology.