A 39-year-old male presented with bilateral painful shin swellings, flu-like symptoms, weight loss, drenching night sweats, diffuse alopecia and an erythematous maculopapular rash with slight desquamation to the face, arms and upper trunk. During further work-up, he presented acutely to the local emergency eye clinic with erythematous and painful eyes.
Plain radiographs of the lower limbs demonstrated a well-defined area of cortical expansion and sclerosis on the anterior aspect of the right tibia with an ill-defined area of cortical erosion and periosteal reaction on the anterior aspect of the left tibia with overlying soft tissue swelling. Magnetic resonance imaging of both lower limbs revealed bilateral anterior tibial periosteal reaction, cortical thickening and bone marrow oedema, more on the right side. Computed tomography of the neck, thorax, abdomen and pelvis demonstrated no organomegaly, lymphadenopathy or lytic bone lesions but did demonstrate bilateral lower lobe nodular consolidation.
Syphilis is a sexually transmitted infection caused by the spirochete Treponema pallidum [1]. The number of new primary, secondary and early latent syphilis infections diagnosed by specialist sexual health services in England alone has increased from 2646 cases in 2010 to 7900 in 2019 [2].
Primary infection is characterised by the development of a painless ulcer called a chancre, which may go unnoticed by the patient [3]. A rash and/or systemic symptoms are seen in secondary syphilis, which if untreated is followed by a latent period of infection [3]. Presentations of tertiary syphilis, such as neurosyphilis, can occur decades after the primary infection [3].
Skeletal features of syphilis may be identified on imaging at all stages of infection [4]. Although bone involvement is well documented in congenital and tertiary syphilis it is comparatively rare in secondary syphilis [4-8]. The skull and long bones, particularly those of the lower limbs, are most commonly affected [4,7]. In disseminated syphilis infection spirochetes may be deposited within the medullary cavity and/or periosteum, inducing a perivascular inflammatory response which causes the radiological findings of periostitis and/or osteolytic bone lesions [1,4,7,9]. However, the degree of bone changes identified on imaging is usually more severe than the clinical symptomatology [10]. Bone scintigraphy may identify increased bone uptake at sites of disease involvement even in the absence of radiographic abnormality [1,7,9]. Computed tomography and magnetic resonance imaging also identify more bone lesions than plain radiography and should be considered in patients with long bone pain and no corresponding radiographic findings. [1,7,8].
Bone pain typically improves within days of initiating appropriate antibiotic therapy [7] but resolution of the radiological findings can significantly lag behind the improvement of clinical symptoms [1].
In our case histopathology from an incisional biopsy of the maculopapular rash from the patient’s neck was consistent with secondary syphilis, which was subsequently confirmed serologically. Local recommended treatment for acquired syphilis is with intramuscular penicillin, or a tetracycline if there is a history of penicillin allergy [3,7]. Follow-up computed tomography examination of the patient’s thorax three months after the initiation of antibiotic therapy revealed a marked improvement of the nodular consolidation.
In the appropriate clinical setting, syphilis should be considered in the differential diagnosis for patients presenting with generalised systemic symptoms, bone pain particularly affecting the limbs and radiological evidence of destructive bone lesions and/or periostitis [4].
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Secondary acquired syphilis
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1. X-ray and MRI of the lower extremity (tibia): There is noticeable thickening of the tibial cortical bone and prominent periosteal proliferation. Mild local soft tissue swelling is observed, suggesting periostitis or possible bony infiltration. MRI shows abnormal signals in the tibial cortex and bone marrow, with slightly elevated or heterogeneous local signal changes, consistent with an inflammatory lesion or infectious bone process.
2. Chest CT: Patchy or nodular lesions are scattered throughout both lungs, some presenting as nodules or irregular shadows with unclear boundaries, indicating possible diffuse or multifocal pulmonary lesions. No obvious large cavitations or significant hilar lymphadenopathy are noted in the lungs.
In summary, considering bilateral tibial periostitis, pulmonary lesions, cutaneous papular rash, hair loss, night sweats, and serological findings, the most consistent etiology is “Secondary syphilis with skeletal involvement.”
Based on imaging findings (periostitis and nodular lesions in the lungs), clinical symptoms (bilateral lower leg pain, fever, weight loss, night sweats, facial and trunk rash, and painful ocular involvement), and laboratory/histopathological results (skin biopsy and syphilis serology), the diagnosis is: Secondary Syphilis (with skeletal and pulmonary involvement).
1. Pharmacological Therapy:
· The first-line treatment is intramuscular benzathine penicillin or, in penicillin-allergic patients, tetracycline-class antibiotics as an alternative. In cases of ocular inflammation, significant skeletal damage, or other organ involvement, systemic or local corticosteroids may be added to reduce the inflammatory response.
· Clinical symptoms such as bone pain and systemic manifestations often improve quickly after treatment; however, radiological changes may take longer to resolve. Regular follow-up of imaging progression and serological titer changes is recommended.
2. General Supportive Measures:
· Ensure a balanced diet, rich in protein, vitamins, and minerals. Maintain adequate fluid intake.
· Prioritize adequate rest, avoid exhaustion and staying up late, and support overall immune function.
3. Rehabilitation and Exercise Prescription:
Since the patient has systemic infection and tibial periostitis, initial management involves rest and light activities, gradually increasing exercise intensity:
· Early Stage (severe symptoms, early in treatment): Recommend home-based exercises such as leg elevation, gentle ankle flexion/extension, and mild stretching, once or twice daily for 5–10 minutes each session. The intensity should not cause pain or increased fatigue.
· Middle Stage (after symptom relief): Gradually incorporate walking sessions of 15–20 minutes daily or every other day, at a moderate pace, either on level ground or a treadmill. Add simple resistance exercises with elastic bands to build lower limb strength, 8–10 repetitions per set, 2–3 sets each session.
· Late Stage (stable symptoms, significant improvement in periostitis): Under the guidance of medical and rehabilitation professionals, engage in moderate-intensity aerobic exercises (such as cycling or brisk walking) three to five times per week, about 30 minutes each session. Continue lower limb and core strengthening, increasing weight-bearing and training volume step by step following the FITT-VP principle (Frequency, Intensity, Time, Type, Volume, and Progression).
· During the entire recovery period, if severe pain, redness, or systemic discomfort reappears, reduce or pause exercise and promptly consult a physician.
This report is based on the existing clinical and imaging data for analysis and serves as a reference. It does not replace an in-person consultation or professional medical advice. If there are any changes in condition or further questions, please seek timely medical attention or consult the appropriate specialist.
Secondary acquired syphilis
