SKIN 
 

July 2022     Volume 6 Issue 4 
 

(c) 2022 THE AUTHORS. Published by the National Society for Cutaneous Medicine. 351 

SKIMages 
 

 

An Unusual Clinical Presentation of Cutaneous Syphilis 
 

Tue Felix Nguyen, BS1, Anaya Shah, BS1, Bahar Momin, BBA1, Marie Vu, BSA1, John 
Browning, MD2  
 
1UT Health San Antonio, Long School of Medicine, San Antonio, TX  
2Department of Dermatology, UT Health San Antonio, San Antonio, TX  
 

 
 

 
Figure 1: Annular, friable violaceous plaque with surrounding erythematous raised border with solitary nodules 
containing pinpoint petechiae 

 
 
A 33-year-old Black homosexual male 
presented with a plaque that appeared 
four months after he injured his hand on 
a metal railing under his car seat. A 3.0 x 
3.5 cm well-defined, annular friable 
violaceous plaque with surrounding 
erythematous raised border with solitary 
nodules containing pinpoint petechiae 
was seen on physical examination 

(Figure 1). His medical history was 
significant for HIV, and he admitted to 
stopping his antiretroviral treatment two 
months prior to presentation. Similar 
appearing lesions were present on his 
back and scrotum. The initial differential 
diagnosis included a deep fungal 
infection, granuloma annulare, Kaposi's 
sarcoma, and neutrophilic dermatosis of 



SKIN 
 

July 2022     Volume 6 Issue 4 
 

(c) 2022 THE AUTHORS. Published by the National Society for Cutaneous Medicine. 352 

the hands. Minocycline 100 mg twice 
daily for 14 days was prescribed, with 
notable improvement at the two-week 
follow-up. Histopathology showed 
psoriasiform epidermal hyperplasia with 
elongated thin rete ridges and a 
superficial to mid dermal perivascular 
and periadnexal infiltrate of lymphocytes, 
histiocytes, some neutrophils, and 
numerous plasma cells. The infiltrate 
obscured the dermo-epidermal junction, 
which was associated with vacuolar 
alteration and necrotic keratinocytes. 
Spirochete immunohistochemistry was 
done and yielded the presence of rare 
spirochetes within the specimen (Figure 
2). The diagnosis of syphilis was made, 
and the health department was contacted 
for further treatment. 
 

Figure 2: Positive spirochete 
immunohistochemistry stain in biopsy 
specimen 
 
Syphilis is a sexually transmitted 
infection (STI) caused by the bacteria 
Treponema pallidum that presents with 
symptomatic and asymptomatic stages. 
The incidence of syphilis has been 
increasing since the early 2000s, when 
the rates of syphilis were at their historic 
lowest. Between 2019 to 2020, the rate 
of syphilis increased by 6.8%. Men 

especially are vulnerable, as many cases 
are seen in men who have sex with men.1 
Co-infection with syphilis and HIV is 
highest in African Americans, which may 
alter the clinical presentations of either 
disease.2 Syphilis is known as the “great 
mimicker,” both clinically and 
histologically; it can present differently 
depending on the stage of the infection 
and when the biopsy was taken. 
Diagnosis of syphilis is made by a 
screening rapid plasma reagin test (RPR) 
followed by a more specific fluorescent 
treponemal antibody test absorption test 
(FTA-ABS).  
 
Cutaneous manifestations of syphilis are 
often atypical and even more variable 
within skin of color (SOC) patients, 
further complicating the diagnostic 
process. Reports of papulosquamous 
syphilis have presented in an 
ichthyosiform photo-distributed pattern 
within Black populations.3 Similarly, 
syphilitic alopecia in Caucasian and SOC 
patients may often mimic alopecia areata 
with its “moth-eaten,” non-scarring 
distribution.4 Due to the variance of 
syphilis and how it can resemble other 
conditions, misdiagnosis without 
additional testing can delay treatment 
and worsen disease progression.  
 
Our case highlights an unusual 
presentation of cutaneous syphilis in a 
vulnerable population and how a 
diagnosis is difficult based on clinical 
presentation alone. Serologic testing or a 
biopsy is necessary to make a proper 
diagnosis. While intramuscular 2.4 
million units benzathine penicillin G 
single dose remains the gold standard of 
treatment, minocycline has been shown 
to be an effective alternative therapy for 
early syphilis if penicillin is unavailable.5



SKIN 
 

July 2022     Volume 6 Issue 4 
 

(c) 2022 THE AUTHORS. Published by the National Society for Cutaneous Medicine. 353 

Conflict of Interest Disclosures: None 
 
Funding: None 
 
Corresponding Author: 
Tue Felix Nguyen, BS 
UT Health San Antonio  
Long School of Medicine 
San Antonio, TX 78229 
Email: nguyent47@livemail.uthscsa.edu 

 
 
References: 
1. National Overview of STDs, 2020. Center for 

Disease Control and Prevention. 

https://www.cdc.gov/std/statistics/2020/overvi

ew.htm#Syphilis. Accessed May 26, 2022.  

2. Funnyé AS, Akhtar AJ. Syphilis and human 

immunodeficiency virus co-infection. J Natl 

Med Assoc. 2003;95(5):363-382. 

3. Ivars Lleó M, Clavo Escribano P, Menéndez 
Prieto B. Atypical Cutaneous Manifestations 
in Syphilis. Manifestaciones cutáneas 
atipícas en la sífilis. Actas Dermosifiliogr. 
2016;107(4):275-283. 
doi:10.1016/j.ad.2015.11.002 

4. Doche I, Hordinsky MK, Valente NYS, Romiti 
R, Tosti A. Syphilitic Alopecia: Case Reports 
and Trichoscopic Findings. Skin Appendage 
Disord. 2017;3(4):222-224. 
doi:10.1159/000477415 

5. Shao LL, Guo R, Shi WJ, et al. Could 
lengthening minocycline therapy better treat 
early syphilis?. Medicine (Baltimore). 
2016;95(52):e5773. 
doi:10.1097/MD.0000000000005773