Teaching Case

A 58-year-old woman who had worked as a store operator presented with recurring episodes of tenderness on the volar aspect of her left hand for the past two years, which she described as a “burning” or “tingling” sensation. She also described the appearance of subcutaneous tender lumps during those episodes, mainly around the metacarpophalangeal joints and proximal fingers, which then resolved. On presentation, her physical examination was unremarkable, and there was no other relevant past medical history.

Magnetic resonance (MR) imaging showed multiple millimetric, nodular, round lesions in the subcutaneous plane of the volar surface of the left hand, in greater size and number near the metacarpophalangeal joints and phalanges. The lesions showed very high signal intensity on fluid-sensitive sequences and signal intensity similar to muscle on T1-weighted sequences.

Background

Pacinian corpuscles are end-organ mechanoreceptors that respond to changes in pressure and vibration. They are found throughout the body but are most numerous and most tightly grouped in the deep dermis of the volar surface of the hands and feet [1–4]. Normal Pacinian corpuscles are round or ovoid in shape, measure about 1–2 mm in length and are mostly located near the metacarpophalangeal joints and proximal fingers [2–4]. Maximum normal density is 3 to 5 corpuscles per square centimetre [2].

Pathology related to Pacinian corpuscles is rare; there are only a few cases described in the literature, and terminology is inconsistent [2]. “Pacinian corpuscle hyperplasia” refers to an abnormal increase in and/or density of Pacinian corpuscles [1]. The pathogenesis of this condition remains unclear but prior repetitive trauma has been implicated as a potential cause [2].

Clinical Perspective

Pacinian corpuscle hyperplasia predominantly affects women with a mean age of presentation of 49.5 years [1]. It often presents as palpable, subcutaneous tender nodules on the volar aspect of the hands, near the metacarpophalangeal joints and proximal fingers [1,2]. Pain, tenderness, mass sensation, swelling and sensory changes are possible symptoms [1]. Nodules and associated symptoms may spontaneously resolve and later reappear [1,2].

Imaging Perspective

On MR imaging, an increase in the size and number of Pacinian corpuscles is suggestive of Pacinian corpuscles hyperplasia. They appear as multiple nodular lesions on the subcutaneous plane of the volar aspect of the palm and fingers, which show high signal intensity on fluid-sensitive sequences and are isointense to skeletal muscle on T1-weighted sequences. Post-gadolinium administration enhancement is variable [1]. On US, multiple round hypoechoic lesions in the subcutaneous plane may be seen [5]. Although histopathological examination remains necessary to establish a definitive diagnosis [1], typical MR and US findings are very suggestive of this condition in the appropriate clinical setting.

Outcome

Surgical excision is the mainstay of treatment and is curative in the majority of cases [2]. In our case, management consisted of analgesia and clinical follow-up.

Take Home Message / Teaching Points

Pacinian corpuscle hyperplasia is a rare condition that should be considered in the differential diagnosis of tender subcutaneous nodules on the volar aspect of the digits or distal palms. MR and US findings are complementary and are very suggestive of this condition in the appropriate clinical scenario.

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