Can I ask though... is the only thing we don't want it to be is a melanoma? Also what do you mean by systemic disorders?
Thanks I will go see a dermatologist to put it to bed. Thank you
Hello,
Thanks for posting your query.
I can understand your concern for the longitudinal brown stripe on the nail. I have checked the photographs and it looks like melanonychia striata. It most often occurs because of increased production of melanin by melanocytes in the nail matrix.
Most people present with a history of asymptomatic hyperpigmentation of the nail plate. The other harmless possibility which I can think of is melanotic macule of the nail unit.
The causes of melanonychia striata are many and most of them are non serious which include physiologic longitudinal melanonychia, systemic disorders, trauma, inflammatory disorders, fungal infections, drugs, and benign melanocytic hyperplasias. However one of the concerning causes of this disorder is subungual melanoma.
I can understand your concern but to completely rule it out, an examination by a dermatoscope is needed. The features that most commonly occur with melanoma include a brown background hue, the presence of irregular longitudinal lines, and the presence of micro-Hutchinson sign which has been described as pigmentation of the cuticle that is only appreciable with use of a dermatoscope.
Moreover if infectious etiology is suspected then a nail plate clipping can be sent for histologic analysis and appropriate cultures. For the same I would suggest to get it examined from a dermatologist.
Hope that this information helps and hope that you will get better soon.
Wishing you good health.