As you described lesions occuring on calves ,probably would be ANGIOKERATOMA
There are many types, in your case it is solitary or sporadic angiokeratoma.
Sometime, it may be confused with malignant melanoma
If there is doubt, biopsy may be done.
The lesions are actually composed of ectatic blood vessels.
The surface of the lesions is tough and keratotic.
I usually do electrocautery under local anaesthesia in my patients having angiokeratoma.
Surgical excision,cryotherapy and laser ablation
are the other methods of treatment.
There is no medical treatment .
You consult dermatologist
for firm diagnosis and then treatment.
I hope you got my answer.
Dr. Ilyas Patel MD