These accumulations are found in the peripheral lung of a 5 year old dog that was part of research for an entirely different topic.  The identification of the cell was not really possible, there were not absolute defining features, except there were mitochondria, perhaps a lipid droplet (cell membrane is obscure around this area), dense coated endocytic vesicles,  rough endoplasmic reticulum, and it is adjacent to a cell(s) with microvilli, basement membrane, and alveolar space. What it is, I have no clue.

neg 9931, blcok 24669, dog 5 yr, original mag 21750 x 4 pole piece V seimens 1A