A Skin Lesion with Loss of Sensation

choi

Lisa Sanders, The Man Had a Spot on His Face That Would Not Go Away. He Was Shocked to Discover That He Had a Disease That He Thought No Longer Existed. New York Times Magazine, Feb 17, 2019
https://www.nytimes.com/2019/02/ ... longer-existed.html

Quote:

"Standing in front of the bathroom mirror in his home outside Asheville, NC, he turned his head and touched an area on his cheek just in front of his ear. He could feel the smooth, slightly raised surface, but it was on the side of his face, in a spot that was hard for him to see. It was slightly pink, about the size of a 50-cent piece, with irregular borders.

"He had [had] a bad case of psoriasis that his dermatologist had only gotten a handle on a couple of years before when he started him on a new medication called Humira. Once he started the twice-monthly injections, the scaly lesions on his skin had practically melted away. He'd never had psoriasis on his face * * *

"The [skin] biopsy [of the pink legion] showed that the tissue contained structures known as granulomas. These are benign collections of white blood cells, often characterized as the body’s effort to wall off something perceived as foreign — a bacterium or an object — that can’t be eliminated.

"The patient made an appointment with Mark Hutchin, a young dermatologist * * * He went over the story of the sudden appearance of this strange spot and the weird numbness in that part of his face and the lower half of his ear. * * * Hutchin examined the man carefully. What about this little bump, here on your neck? he asked the man. Oh, that’s always been there, the patient told him. No, the doctor disagreed. I think this is new. * * * His fingers recognized the bumpy linear structure he felt in the man’s neck as some kind of swelling of the great auricular nerve — the pipeline carrying sensory information from the ear and surrounding skin back to the spine. If the swelling compressed that nerve, that would explain why the man’s ear and face felt numb. The combination of this growth on the skin and the involvement of the nerve tissue suggested one disease in particular.

Note:
(a) In the table of content, the Magazine said, "Lisa Sanders is an internist and associate professor at Yale School of Medicine. She writes the Diagnosis column, which is being developed into a Netflix documentary scheduled to be released this summer."

So she was recently elevated to associate professor, from assistant professor.
(b)
(i) After some decades, progress in leprosy research is limited, so I do not have basic research to offer you, about leprosy.
(ii) Back in Taiwan, I read a news report that a certain former government-operated leper colony was to close, whose residents did not know how to live in the outside world. An interviewee stated that when she was a little girl in colonial Taiwan, a Japanese police spotted a skin legion on her leg and, with that, a diagnosis of leprosy and forcifully committed to the institution ever since. As far as I can recall, the report did not describe the skin legion, but I realized leprosy has a distinguishing skin lesion.  
(iii) Upon reading the last quotation, specifically the numbness part, I knew it was leprosy.

(c) skin lesion(s) could be a single or multiple patch of pink or whitish (due to depigmentation) color, or a single or multiple skin nodules of skin color. In all, affected skin loses sensation, and biopsy shows (live) bacteria in macrophages.
(i) Leprosy. American Osteopathic College of Dermatology, undated.
https://www.aocd.org/page/Leprosy

This page is poorly written; there is no need to read text. However, the third and last photo shows a skin patch exactly the same as the described in the NYT article.
(ii) Walker SL and Lockwood DNJ, The Clinical and Immunological Features of Leprosy. British Medical Bulletin, 77-78: 103–121 (2006)https://academic.oup.com/bmb/article/77-78/1/103/324572
https://academic.oup.com/bmb/article/77-78/1/103/324572
("Tuberculoid disease is characterized by a single or very few lesions. These are macules or plaques with well-defined edges (Fig. 2). In dark skin, hypopigmentation predominates over the erythema or copper colour more usually seen in lighter skin. The lesions are frequently scaly, dry, hairless and anaesthetic. The anaesthesia is due to destruction of dermal nerve fibres")

(d) There is no need to read the rest of the following text.
(i) Leprosy. World Health Organization (WHO), undated
https://www.who.int/lep/leprosy/en/
("When M leprae was discovered by [Norwegian physician] GA Hansen in 1873, it was the first bacterium to be identified as causing disease in man [in this case, leprosy]. However, treatment for leprosy only appeared in the late 1940s with the introduction of dapsone")
(ii) Diagnosis of leprosy. WHO, undated
https://www.who.int/lep/diagnosis/en/
("Diagnosis of leprosy is most commonly based on the clinical signs and symptoms. These are easy to observe and elicit by any health worker after a short period of training. * * * In an endemic country or area, an individual should be regarded as having leprosy if he or she shows ONE of the following cardinal signs:
• skin lesion consistent with leprosy and with definite sensory loss, with or without thickened nerves
positive skin smears
• The skin lesion can be single or multiple, usually less pigmented than the surrounding normal skin. Sometimes the lesion is reddish or copper-coloured.
* * * Sensory loss is a typical feature of leprosy. * * * Thickened nerves, mainly peripheral nerve trunks constitute another feature of leprosy")
(A) The last quotation of this NYT article first talked about "bump," then "bumpy linear structure," the latter of which sounds like a thickened nerve (great auricular nerve, that is) to me.
(B) The en.wikpedia.org page for great (or greater) auricular nerve has a cluttered anatomy. Better Google that nerve, and see its course. This nerve does NOT carry sound perception, which starts at inner ear and stays within the skull in a nerve called vestibulocochlear nerve.
(iii) Transmission of Leprosy. WHO undated
https://www.who.int/lep/transmission/en/
("More recently the possibility of transmission by the respiratory route is gaining ground [as opposed to contact]. * * * Even in the absence of specific treatment, a majority of patients, particularly of the tuberculoid and indeterminate types, tend to get cured spontaneously. An earlier study in India had shown that over a period of 20 years, the extent of spontaneous regression among children with tuberculoid leprosy was about 90%.