PS

*lam(a)ṯ̣- - eruption (on the skin), white spot (SED I No. 179)

Akkadian
lamṣatu - a skin eruption (CAD L 68, AHw. 533)
The other meaning is ‘a fly’ (CAD L 68. AHw. 533 translates the word as ‘eine grosse Mücke’; as for the contexts in which this meaning does not fit, the translation given is ‘Schwellung durch Mückenstich’.
Arabic
lamaḏ̣-, lumḏ̣at- - a whiteness in the lower lip of a horse (BK 2 1026, Lane 2674)
Geez
lamṣ - leprosy, scab (CDG 316)
Tigrinya
lämṣi - leprosy that produces whitish spots on the skin, but does not gnaw at the flesh (Bass. 19)

It can be a loan from Gez. lamṣ - leprosy, scab. 

Amharic
lämṭ - leprosy (AED 52)

It can be a loan from Gez. lamṣ - leprosy, scab. 

Amharic
lämṭo - horse with white nose and muzzle (AED 52)
Muher
lämṭ - leprosy (EDG 380)
Masqan
lämṭ - leprosy (EDG 380)
Gogot
lämṭ - leprosy (EDG 380)
Soddo
lämṭ - leprosy (EDG 380)