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SynopsisAchenbach syndrome, also known as paroxysmal finger hematoma or acute idiopathic blue finger, is a rare and benign disorder characterized by the sudden onset of blue discoloration on the ventral surface of one or more fingers. The skin discoloration is usually preceded by sharp pain, numbness, and/or itching. It can later be accompanied by edema and a cold sensation.
The most commonly affected areas are the proximal and middle phalanges of the index and middle fingers, with sparing of the fingertips. While it most frequently involves the fingers, it has also been described on the palms and toes. The condition predominately affects women between 30 and 50 years.
Achenbach syndrome usually develops spontaneously without an identifiable trigger. It can sometimes occur following minor trauma. It involves the formation of a hematoma that is generally 1-2 cm in diameter. The hematoma may expand in size and involve the palm.
Although reduced capillary resistance and vascular fragility have been proposed, the etiology remains unclear. No associating coagulation disorders or consistent abnormal radiographic findings have been implicated. The symptoms are likely secondary to the infiltration and compression effects of extravasated blood. While most cases occur without any associated findings, acrocyanosis, gastrointestinal diseases, biliary diseases, and migraine headaches have been described in some cases. However, a true pathophysiologic relationship between Achenbach syndrome and these entities has not been established.
Achenbach syndrome is a self-limiting and nonurgent condition. Complete resolution typically occurs within 4 days but can take up to 2 weeks. Recurrent episodes can occur at variable time intervals.
I73.89 – Other specified peripheral vascular diseases
238824006 – Paroxysmal hematoma of the finger
Differential Diagnosis & PitfallsWhile Achenbach syndrome is a benign condition, it is important to rule out urgent alternative diagnoses. The differential diagnosis includes:
- Peripheral arterial disease – Decreased pulses would be observed, and cyanosis is usually present on the tips of the fingers.
- Cholesterol emboli – More commonly seen in men with histories of atherosclerosis, hypertension, and diabetes. Ulceration and gangrenous changes may be present.
- Thromboangiitis obliterans (Buerger disease) – Mainly associated with tobacco use and typically seen in men. Ulceration and gangrenous changes of the digits may ensue.
- Raynaud phenomenon – Usually involves repeated and chronic episodes that occur in the context of cold temperature or stress. The skin demonstrates pallor and cyanosis followed by erythema.
- Type 1 cryoglobulinemia – Purpura of the distal digits is seen.
- Venous thrombosis – Presents as a bluish and painful nodule in the proximal interphalangeal joint.
- Acrocyanosis – Caused by decreased deoxyhemoglobin in the peripheral vasculature. It affects digits symmetrically and is exacerbated by cold weather.
- Autoerythrocyte sensitization (psychogenic purpura) – Most commonly seen in the lower extremities. There is a strong association with psychiatric disorders.
- Frostbite – Usually results in white or yellow skin that hardens and can progress to gangrene formation in the context of cold exposure.
- Perniosis (chilblains) – Characterized by erythematous / violaceous and pruritic papules that develop after exposure to cold weather.
- COVID-19 pseudo-chilblains (see COVID-19)
- Trauma – Bruises are usually explained by a preceding traumatic event.
- Thoracic outlet syndrome – Occurs due to the compression of the brachial plexus and/or subclavian vessels. Absent pulses would be noted.
- Erythromelalgia – Most commonly occurs in the feet, although the hands can sometimes be involved. Warm, erythematous extremities are observed.
- Dermatitis artefacta