Answer:
No, elective node dissection need not be done for a lesion less than 1 mm because the incidence of lymph nodal metastases is between 5-10%. A 5-mm thick lesion has a greater than 65% chance of having positive lymph nodes, and the prognosis (which is very poor) is not really affected if the dissection is done after nodes are palpable. Disection in this case would be performed to prevent fungation and its attendant implications for quality of life.
The issue of ELND for a lesion 1-4 mm in thickness is more complicated. One way around this is to do a sentinel node biopsy for all these lesions and proceed with a node dissection if the frozen section is positive.