Confusion abounds in regard to the terms "follicular mucinosis" and "alopecia mucinosa," not only concerning definition and essential character, but of relationships between them, themselves, on one hand and between them and mycosis fungoides on the other. We address here those issues in methodical fashion, first in historical perspective by review, scrupulously and critically, of what has been said in the many articles devoted to the subject; we next tell how the terms "alopecia mucinosa" and "follicular mucinosis" came to be and how they are employed currently; we then set forth our own observations pertinent to clinical, histopathologic, and biologic aspects of the condition called, conventionally, "alopecia mucinosa," those being based on our own findings in sections of tissue cut from 54 biopsy specimens taken from 45 patients, all of them having been signed out previously as "follicular mucinosis;" we proceed to forge clinico-pathological correlation of lesions in 14 of those 45 patients, utilizing in that effort assessments, by examination grossly and microscopically, of attributes in the very same lesion, and, last, we propose a concept, and a terminology that derives from it, that synthesizes all which is known now about "alopecia mucinosa" and "follicular mucinosis," in particular the relationship of "alopecia mucinosa" to mycosis fungoides, including "follicular," "syringotropic," and erythrodermic manifestations of it. In short, we affirm that so-called alopecia mucinosa is but one of many morphologic manifestations of mycosis fungoides.