Teaching Case

A 14-year-old boy with no prior medical history presented with a two-week history of soft tissue swelling on the second phalanx of his left index finger. He reported mild tenderness, minimal redness, and no local warmth. Additionally, he mentioned exposure to cold weather. The consultation took place during wintertime.

An X-ray revealed small radiolucent areas in the middle phalanx, focal periostitis, and soft tissue swelling. The patient underwent a contrast-enhanced MRI, which demonstrated small lytic cortical bone lesions enhancing with contrast, a diffuse hypovascular appearance of the bone marrow with decreased T1 signal and increased signal on DP fat sat sequences, as well as soft tissue swelling with oedema in the regional area. An ultrasound examination revealed oedema with increased subcutaneous and dermal vascularity and cortical irregularities in correlation with the X-ray findings.

A fluoroscopy-guided biopsy showed bone necrosis without atypia.

A follow-up X-ray showed advanced reparative signs at 7 months from the onset of symptoms.

Phalangeal microgeodic syndrome in childhood and adolescence is a rare and benign condition characterized by the formation of small cavities in the phalanges of the fingers [1]. It was first reported in 1970 in a series of 5 cases [2].

Pathophysiology

While not fully understood, it is suggested to involve bone resorption and destruction in response to exaggerated peripheral circulatory impairment following exposure to cold. Cooling is believed to be a significant triggering factor, as the disease tends to manifest during cold months [1]. Persistent swelling of the affected finger with mild pain is a common presenting symptom [3]. This is consistent with the patient's history in our case, as the symptoms occurred during the winter, and upon specific questioning, he reported direct exposure to cold weather on his hands.

Diagnostic Pearls

The key radiographic finding is the observation of multiple small, well-defined, round osteolytic areas that resemble geodes in the medullary and cortical regions of the affected phalanges; these lesions tend to be larger in the proximal metaphysis, as reported. Cortical irregularities and periosteal reaction can also be observed in the affected phalanges, without bone expansion [1,4,5]. Diagnosis can be established based on a compatible clinical history and X-ray, but given the rarity of this condition, additional studies such as MRI, biopsy, or nuclear medicine scans are often requested [6]. The most common MRI findings include low signal intensity in the bone marrow of the affected phalanges on T1-weighted images and high signal intensity on fat-suppressed T2-weighted images. Soft tissue oedema adjacent to the affected bone is also frequently present, suggesting an associated inflammatory response [4].

Prognosis

Regarding treatment, most cases of this syndrome resolve spontaneously within weeks to months, requiring no medical intervention and resulting in no long-term consequences [1,3]. This was also the case with our patient, who only received analgesia for the mild pain he experienced.

Awareness of this condition is crucial to prevent unnecessary diagnostic studies and treatments [6].

All patient data have been completely anonymised throughout the entire manuscript and related files.