Can CTE be distinguised from DUPA with a scalp examination alone?

In in my opinion, a hair loss expert should be able to distinguish between chronic telogen effluvium and diffuse unpatterned alopecia with a good examination including dermatoscope and history. PRP hair MD.com

Diffuse unpatterned alopecia (DUPA) can generally be differentiated from chronic telogen effluvium (CTE) by careful review of the patient's history, and examination of the scalp using dermoscopy. Rarely a biopsy can be confirmatory but usually this is not needed.On history, patients with DUPA report diffuse thinning. They usually dont have all that much in terms of increased shedding. Typically, the hair loss is first noticed between 15-24. Examination of the scalp shows variation in the sizes of follicles. We call this anisotrichosis. Some hairs are thick and some are thin. The miniaturization occurs all over the scalp. A biopsy shows a terminal to vellus ratio of much less than 4:1.In contrast to DUPA, patients with CTE are usually a bit older when they first notice hair loss. Their stories are markes by concerns about massive shedding that comes and goes, some weeks good and some weeks bad. Patients with CTE don't usually look like they have haor loss to others whereas patients with DUPA often do look like they have hair loss. In CTE, examination shows terminal thick hairs. The temples may or may not show recession but often do in the setting of CTE. A biopsy shows T: V ratios that are high - and ratios 8:1 or higher are suggestive of CTE.In summary, DUPA and CTE can usually be easily differentiated with careful examination and review of the patient's story.

DUPA and CTE are distinguishable from one another pretty reliably with a scalp exam and history taking.  For instance, DUPA does not always have significant shedding while CTE does not always have significant miniaturization.  The kicker is that all hair loss conditions can co-exist, and androgenetic alopecia can complicate the diagnostic picture with both of these.  Find someone who really knows their stuff and they should be able to tell you what is going on.  
Good luck!

The diagnosis of DUPA is made by an examination of the hair and scalp with a microscope which will show miniaturized hair throughout, including the donor area while CTE does not