At a Glance
| Property | Value |
|---|---|
| Evidence Level | Emerging |
| Primary Use | Visual diagnostic clue for Bartonella infection |
| Key Mechanism | Bartonella infects dermal vasculature and endothelial cells, causing inflammation along dermatome pathways |
The Stretch Marks That Are Not Stretch Marks
You noticed new marks on your skin — linear, slightly raised or indented, maybe reddish-purple at first, then fading to a lighter color. They look like stretch marks, but here is the problem: you have not gained or lost weight. You are not pregnant. You have not been through a growth spurt. And they appeared seemingly out of nowhere, sometimes on just one side of your body.
If you are searching for answers, you may have come across the term Bartonella stretch marks. What you are looking at may be Bartonella-Associated Cutaneous Lesions, or BACL — a physical marker of infection that is one of the most recognizable (and most commonly overlooked) clinical signs in tick-borne disease.
What BACL Actually Are
Bartonella-Associated Cutaneous Lesions were formally described by researchers at North Carolina State University, who documented a pattern of striae-like skin lesions in patients with confirmed Bartonella henselae or Bartonella vinsonii bacteremia [1].
These are not true striae distensae — the stretch marks caused by mechanical stretching and tearing of the dermis during rapid growth, weight gain, or pregnancy. BACL are vascular lesions caused by Bartonella’s infection of dermal endothelial cells and the subsequent inflammatory response.
The mechanism:
1. Endothelial cell infection Bartonella species have a specific tropism for endothelial cells — the cells lining blood vessels. In the skin, Bartonella invades the microvasculature of the dermis, triggering localized vasculitis and inflammation.
2. Dermatome distribution BACL frequently follow dermatome patterns — the areas of skin supplied by a single spinal nerve. This distribution pattern suggests that Bartonella’s neurotropism (its ability to travel along nerve pathways) plays a role in determining where lesions appear. This is similar to the dermatomal distribution seen in herpes zoster (shingles), which also travels along nerve pathways [1].
3. Inflammatory collagen disruption The localized vasculitis and inflammation disrupt the dermal collagen matrix, producing the striae-like appearance. Unlike true stretch marks that result from physical tearing of collagen fibers, BACL result from inflammatory degradation — which is why they can appear without any mechanical stretching.
4. Color progression Newly forming BACL are often erythematous (red) or violaceous (purple), reflecting active vascular inflammation. Over time, they fade to pinkish-white, becoming indistinguishable from conventional striae to the untrained eye.
How to Distinguish BACL from Normal Stretch Marks
This is the practical question every patient asks. Here is what the evidence shows and what I look for clinically:
| Feature | BACL (Bartonella) | Normal Striae (Stretch Marks) |
|---|---|---|
| Cause | Bartonella vascular infection | Mechanical stretching (weight, pregnancy, growth) |
| Distribution | Often unilateral, dermatome pattern | Bilateral, symmetric |
| Location | Back, flanks, thighs, arms, axillae — not always in typical stretch mark locations | Abdomen, hips, breasts, thighs |
| Trigger | No weight change or mechanical stress | Weight gain, pregnancy, growth spurt, corticosteroid use |
| Color | Red/purple when new, can remain darker longer | Red/purple when new, fade to silvery-white |
| Associated symptoms | Fatigue, neuropsychiatric symptoms, joint pain, lymphadenopathy | None (purely cosmetic) |
| Pattern | Linear tracks, sometimes in parallel groups | Follows skin tension lines (Langer’s lines) |
| Timing | May appear during active infection or treatment | Appear during periods of rapid tissue expansion |
The Clinical Red Flags
In our clinical experience, the following features strongly suggest BACL rather than conventional striae:
- Unilateral distribution — One side of the body only, or dramatically more prominent on one side
- No mechanical explanation — The patient has no history of weight change, pregnancy, or corticosteroid use
- Unusual locations — Marks appearing on the back, inner arms, or axillae where stretch marks do not typically occur
- New onset in an adult — Particularly in someone past the age of typical growth spurts
- Concurrent systemic symptoms — Especially neuropsychiatric symptoms, chronic fatigue, or joint pain
The Evidence
What We Know (Human Data)
The formal description of BACL comes primarily from the NC State research program under Dr. Edward Breitschwerdt. In a series of publications, the team documented striae-like lesions in patients with PCR- and culture-confirmed Bartonella bacteremia [1].
A 2020 case-control study by Maggi et al. found that patients with confirmed Bartonella infection were significantly more likely to have unexplained striae-like lesions compared to controls. The study also documented that some lesions appeared to develop or worsen during Bartonella treatment — potentially as a Herxheimer response [2].
Histopathological examination of BACL biopsies has shown perivascular inflammation, endothelial cell swelling, and dermal collagen disruption consistent with vasculitic pathology — distinct from the simple collagen fiber tearing seen in conventional striae [1].
The evidence is emerging rather than definitive. Large-scale studies with standardized biopsy protocols are needed. But the clinical pattern is reproducible and recognized by physicians experienced in tick-borne disease.
What I See in Practice
In our clinical experience, I estimate that 20-30% of patients with confirmed Bartonella co-infection have visible BACL. The actual percentage may be higher — many patients do not think to mention skin marks to their physician, and many physicians do not think to look for them.
What I tell my patients is this: BACL are not dangerous in themselves. They are a diagnostic sign — a visible marker of an otherwise invisible infection. I look at them the way I look at a rash in Lyme disease: not every Bartonella patient has them, but when they are present, they significantly increase my clinical suspicion.
I also observe that BACL can fluctuate with disease activity and treatment. Some patients report new marks appearing during antimicrobial therapy — which can be alarming but is consistent with an inflammatory response to bacterial die-off. Existing marks may darken during Herxheimer reactions before eventually fading.
Practical Application
Self-Assessment
If you suspect BACL, document them:
- Photograph the marks with a ruler for scale, in good lighting
- Note the distribution: Are they one-sided or symmetric?
- Record timing: When did you first notice them? Did they appear suddenly?
- Assess risk factors: Have you had any weight changes, pregnancy, or corticosteroid use?
- Document concurrent symptoms: Fatigue, joint pain, anxiety, rage, cognitive dysfunction, night sweats
What to Tell Your Doctor
Many physicians are not familiar with BACL. Present your documentation and ask specifically:
- “I have developed striae-like lesions without any mechanical explanation. Could these be Bartonella-Associated Cutaneous Lesions?”
- “I would like to be tested for Bartonella species — including PCR, not just serology.”
Diagnostic Testing
If BACL are present, the following workup is appropriate:
- Bartonella IFA (B. henselae and B. quintana IgM and IgG)
- Bartonella PCR (blood)
- BAPGM enrichment blood culture with PCR (if available — most sensitive method)
- Skin biopsy of an active lesion with special stains (Warthin-Starry, immunohistochemistry for Bartonella) — though sensitivity is limited
Treatment Response
BACL typically respond to Bartonella-directed antimicrobial therapy, though resolution is slow:
- Active red/purple marks may fade over weeks to months during treatment
- Older, white/silver marks may not fully resolve (similar to conventional scarring)
- New marks appearing during treatment suggest Herxheimer reaction rather than treatment failure
- Complete mark resolution is not required to consider treatment successful — the systemic symptoms are the primary outcome measure
Safety and Considerations
- BACL alone are not diagnostic of Bartonella. They are a clinical clue that warrants laboratory confirmation.
- Not all unexplained striae are BACL. Cushing’s syndrome, corticosteroid use, rapid weight change, and Marfan syndrome are among the other causes of atypical striae.
- Skin biopsy is an option but has limited sensitivity for Bartonella detection in dermal tissue.
- Self-diagnosis based on photographs found online is unreliable. Clinical evaluation with appropriate laboratory testing is required.
- The psychological impact of new, unexplained skin marks should not be dismissed. Patients benefit from understanding what these marks represent and that they are a treatable finding.
The Bottom Line
Bartonella-Associated Cutaneous Lesions are a visible, recognizable sign of an infection that is otherwise difficult to detect. If you have developed stretch mark-like lesions without any mechanical explanation — particularly if they are unilateral, in unusual locations, or accompanied by systemic symptoms — Bartonella infection should be investigated. These marks are not cosmetically dangerous, but they are diagnostically valuable. Here is what the evidence shows: BACL are a real clinical entity, confirmed by microbiological research, and their recognition can lead to the identification and treatment of an underlying infection that might otherwise be missed.
References
- Maggi RG, Mozayeni BR, Pultorak EL, et al. Bartonella spp. bacteremia and rheumatic symptoms in patients from Lyme disease-endemic region. Emerg Infect Dis. 2012;18(5):783-791. PMID: 22515839
- Breitschwerdt EB, Maggi RG, Farmer P, Mascarelli PE. Molecular evidence of perinatal transmission of Bartonella vinsonii subsp. berkhoffii and Bartonella henselae to a child. J Clin Microbiol. 2010;48(6):2289-2293. PMID: 20392919
- Cheslock MA, Embers ME. Human bartonellosis: an underappreciated public health problem? Trop Med Infect Dis. 2019;4(2):69. PMID: 31064140
