Allergic contact dermatitis: This is a common reaction to tattoo ink, especially in older tattoos. The presence of raised lines, scaling skin, and lumps near the tattoo site suggests a chronic allergic response to the ink, which can occur years after the tattoo was applied.

Sarcoidosis: This condition can cause skin lesions and lumps, and while it's less common, it can be associated with tattoos. The presence of lumps on the legs not attached to the tattoo could suggest systemic involvement.
Granuloma annulare: A benign skin condition that can cause lumps and raised lines, potentially triggered by the tattoo ink. It's more common in children and young adults.
Keratoacanthoma: A type of skin growth that can appear as a lump, sometimes associated with tattoos. It's usually benign but can resemble squamous cell carcinoma.

Malignant transformation: Although rare, it's crucial to consider the possibility of a malignant tumor (e.g., squamous cell carcinoma, basal cell carcinoma) arising in or near the tattoo, especially if there are new or changing lesions.
Infectious complications: Such as abscesses or cellulitis, which could be life-threatening if not promptly treated, especially in immunocompromised individuals.
Lymphoma: Certain types of lymphoma can present with skin lesions, and while extremely rare, it's a diagnosis that could have significant implications if missed.

Foreign body granuloma: A rare reaction to the tattoo ink or other foreign materials in the skin, which can cause chronic inflammation and lumps.
Lichen planus: An autoimmune condition that can cause skin lesions and lumps, potentially triggered by the tattoo ink, though this is less common.
Pseudolymphomatous reaction: A rare condition that mimics lymphoma but is actually an inflammatory response, potentially to the tattoo ink.