Never seen these ones in hisec. But this table tells us that it's possible:

http://wiki.eveonline.com/en/wiki/DED_Complex_List

Is it really possible?

Please note: The above data has been compiled from explorer community reports on DED-Complexes and, particularly, from data shared by Elisa Fir. Nevertheless, there may be holes in the data, and it is a work in progress. If you have useful information or data that conflicts with anything here, please feel free to contribute.

Deltolle if i remember correctly ... been there yesterday ... normal accessible via gate key and visible as beacon on overview

DED 5/10 complexes don't spawn naturally in highsec as scannable sigs, however if you get one as an escalation from a (faction) Den anomaly the resulting DED 5 will occasionally spawn in highsec. This is very unusual though its most often in lowsec.

no, you can't find DED5s in hisec.

There is a scan. sig strength of an anomalies in that table... A bit confusing to me... :(

The table you linked contains 'signatures' not 'anomalies'.

Please, read carefully.

"scan. sig strength OF an anomalies"

Now you missed me

The table contains signatures AND their respective signature strengths.
There is nothing about anomalies here.

Ah, got it.
Well... i do believe that any dedspace complex IS an scanable anomaly :)

5/10's that result from escalations are NOT cosmic signatures or anomalies. 5/10's that spawn as cosmic signatures do not happen in hisec.

they used to spawn in hisec anyway as i have done 2 angel red light districts in ani constellation of metropolis ( both 0.5 systems) , altho that was early 2010 and things have changed since then.

i haven't done exploration in nearly a year now and those are the only 2 i ever found and no they weren't escalations. but if i have then surely others have as well