When Maribeth Holzer asked her family doctor about a curious lump in her right armpit, she never suspected it was follicular lymphoma.  Her doctor said it was probably an ingrown hair caused by shaving, or perhaps a blocked pore due to antiperspirant use.

But when a purple, dime-sized spot suddenly appeared on Maribeth’s face, she decided to visit a dermatologist.

“I felt fine,” she says, “but thought I should...