Adrenal gland

Normal adrenal gland. A parasympathetic ganglion is seen to the left. 

From left to right (outside inwards): Glomerulosa, fasciculata, reticularis, then some medulla, the same in reverse sequence to the right

Predominantly the fat, orange cells of fasciculata

Epidermal nevus

'Nevus' is a hamartoma of any element of skin.  So why not the epidermis itself?

Note the prominent papillomatosis, acanthosis and lamellated keratin

Acute lymphoblastic leukemia

A three year old child with weakness and bleeidng

Bone marrow

More bone marrow

Blasts

PAS

PAS; not the 'block' positivity in the center

MPO