Laboratory testing for syphilitic alopecia: Time to renew old habits?
June 4, 2018
I’m not sure how this happened. I used to check several laboratory studies in patients presenting with alopecia, including a rapid plasma reagin (RPR) for syphilis (in addition to a CBC, TSH, iron binding studies, ANA and vitamin D; testosterone and DHEAS would also be obtained if there was a hint of virilization). Now it’s usually just a CBC, ferritin, and TSH.
Dermatologists know that there are three great mimickers that can be included in virtually every differential diagnosis — sarcoidosis, cutaneous T-cell lymphoma, and Osler’s ultimate masquerader — syphilis.
Syphilis is on the rise in recent years, especially in men having sex with men. (1)
I applaud Costa et al for having diagnosed syphilis in the two cases they presented — I probably would have misdiagnosed diffuse alopecia areata. The first was a 14 year- old-girl, with a 4 month history of diffuse and poorly‐defined hair loss in the parieto‐occipital area and a loss of the distal third of the eyebrows (Fournier’s sign). The second was a 23 year-old man, with diffuse, unevenly distributed hair loss for the previous 3 months. Both patients had a positive VDRL (Venereal Disease Research Laboratory, VDRL) and a positive FTA-Abs (fluorescent treponemal antibody absorption); both were treated with benzathine penicillin resulting in complete hair regrowth. (2)
Admittedly, my point of reference is an image of “moth eaten” syphilitic alopecia (SA) appearing in an ancient edition of Andrews. As Tognetti et al state: “SA may clinically mimic a wide range of hair disorders, including alopecia areata (AA), trichotillomania, lichen planus pilaris, tinea capitis, telogen effluvium, and androgenetic alopecia. Thus, the diagnosis may be delayed, especially when SA is the unique manifestation of secondary syphilis and primary syphilis signs are absent or not reported (i.e., essential SA).” (3)
Here is something to chew on — would you have suspected lues in the following case?
Luo and Liu reported a 2‐year‐old boy with a 3‐month history of “moth‐eaten” scalp alopecia. Serological tests showed a positive RPR with a titer of 1:32, and Treponema pallidum particle agglutination (TPPA) positivity. His parents tested negative for syphilis, but his grandmother demonstrated a positive RPR (1:32) and TPPA positivity. Every day the boy’s grandmother chewed food before feeding it to him; apparently this ritual occurs in the poorly educated of rural China. The boy was diagnosed with acquired syphilis via premasticated food; the only symptom was moth‐eaten alopecia. (4)
The current hypothesis supporting the pathogenesis of SA is a vasculitis of peribulbar capillaries causing a perifollicular lymphocytic infiltration with scattered plasma cells that stops the hair cell cycle. The tropism of Treponema pallidum for the hair bulge epithelium and peribulbar capillaries has been demonstrated by scalp biopsies detecting spirochetes in the peribulbar region and penetrating into the follicle matrix. (3)
In conclusion, there are two types of SA: “symptomatic SA” accompanied by other lesions of secondary syphilis and “essential SA” free from any other cutaneous manifestations. (5) Although essential SA is considered extremely rare, I wonder how many cases I have missed. Perhaps it’s time again to routinely check syphilis serologies in patients presenting with non-scarring alopecia.
Point to remember: Consider checking for syphilis in patients presenting with alopecia without other features of lues.
1. Patton ME, et al. Primary and secondary syphilis – United States, 2005-2013. MMWR Morb Mortal Wkly Rep 2014; 63: 402-6.
2. Costa MC, et al. Nonspecific diffuse alopecia as a single manifestation of syphilis infection: Clinical and trichoscopic features. Int J Dermatol 2018; 57: 593-5.
3. Tognetti L, et al. Syphilitic alopecia: Uncommon trichoscopic findings. Dermatol Pract Concept 2017; 7: 55-9.
4. Luo Y, Liu J. Image gallery: Moth-eaten alopecia as the only cutaneous symptom of acquired secondary syphilis in a 2-year-old boy. Br J Dermatol 2017; 177: e227.
5. Cao HL, et al. Moth-eaten essential syphilitic alopecia. QJM 2015; 108: 157-8.
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