What are calcaneal petechiae?
Calcaneal petechiae, also known as talon noir ('black heel'), are a benign condition due to the accumulation of blood in the stratum corneum of the heel. Many other terms have been used to describe these haemorrhagic lesions of the stratum corneum, including subcorneal haematoma, haemorrhagic hyperkeratosis, basketball heel, and tennis heel/toe. Similar lesions can be found on the hands, such as tache noir ('black palm') and PlayStation thumb.
What causes calcaneal petechiae?
Calcaneal petechiae follow repeated pounding or lateral shearing forces causing dilation and rupture of fragile blood vessels in the papillary dermis, micro-haemorrhages, and extravasation of blood cells through sweat ducts into the epidermis. Extravasated red blood cells in the stratum corneum are inaccessible to phagocytic cells. Jumping, sudden stopping, or twisting on the heel are the usual activities that precipitate the bleeding.
Who gets calcaneal petechiae?
As several of the alternative names suggest, calcaneal petechiae are common in adolescent or young adult athletes. Many of the earliest cases were reported in basketball players.
What are the clinical features of calcaneal petechiae?
Calcaneal petechiae present as the sudden onset of lesions with intracorneal haemorrhage. These can vary in colour (red, brown, black), number, size (multiple pinpoint to large single lesions), and location (heel, sole, toe). Calcaneal petechiae are asymptomatic. Paring with a scalpel blade shows the colour is in the shavings and the colour is rapidly removed from the skin.
What are the dermoscopic features of calcaneal petechiae?
Dermoscopy of subcorneal haematomas demonstrates a red-brown colour; brown, red, and black are less commonly seen. The most common pattern of pigmentation is homogenous, followed by globular and parallel ridge. See also Dermoscopy of other non-melanocytic lesions.
Dermoscopy of calcaneal petechiae
How are calcaneal petechiae diagnosed?
Calcaneal petechiae are usually a clinical diagnosis supported by dermoscopy and paring of the lesions without need for a biopsy. Histological assessment of the lesion would show hyperkeratosis and epidermal acanthosis, with focal haemorrhage within the stratum corneum (see Talon noir pathology).
What is the differential diagnosis for calcaneal petechiae?
Appropriate diagnosis of calcaneal petechiae is important as the condition may mimic benign or malignant melanocytic lesions, including acral lentiginous melanoma. Other diagnoses to consider may include viral warts and traumatic tattoo.
Paring of the lesion helps distinguish calcaneal petechiae from these conditions:
- Appearance of normal skin after removal of haemorrhagic material serves as an instant confirmation of the diagnosis
- Melanocytic lesions in the epidermis or dermis will not be completely removed with paring
- Traumatic tattoo marks may not be completely removed with paring
- Pinpoint bleeding from papillary capillaries in warts is seen after paring.
What is the treatment and outcome for calcaneal petechiae?
Following diagnosis, calcaneal petechiae do not require treatment. Calcaneal petechiae resolve spontaneously within 4–6 weeks. They may recur if the triggering skin trauma continues. Paring of the stratum corneum with a scalpel blade will remove the haemorrhagic material without bleeding or pain.