Visualization of intradermal blood vessel structures by dual-wavelength photoacoustic microscopy and characterization of three-dimensional construction of livedo-racemosa in cutaneous polyarteritis nodosa.

BACKGROUND: Photoacoustic microscopy is expected to have clinical applications as a noninvasive and three-dimensional (3D) method of observing intradermal structures. OBJECTIVE: Investigate the applicability of a photoacoustic microscope equipped with two types of pulsed lasers that can simultaneously recognize hemoglobin and melanin. METHODS: 16 skin lesions including erythema, pigmented lesions, vitiligo and purpura, were analyzed to visualize 3D structure of melanin granule distribution and dermal blood vessels. 13 cases of livedo racemosa in cutaneous polyarteritis nodosa (cPN) were further analyzed to visualize the 3D structure of dermal blood vessels in detail. Vascular structure was also analyzed in the biopsy specimens obtained from tender indurated erythema of cPN by CD34 immunostaining. RESULTS: Hemoglobin-recognition signal clearly visualized the 3D structure of dermal blood vessels and melanin-recognition signal was consistently reduced in vitiligo. In livedo racemosa, the hemoglobin-recognition signal revealed a relatively thick and large reticular structure in the deeper layers that became denser and finer toward the upper layers. The numerical analysis revealed that the number of dermal blood vessels was 1.29-fold higher (p<0.05) in the deeper region of the lesion than that of normal skin. The CD34 immunohistochemical analysis in tender indurated erythema revealed an increased number of dermal vessels compared with normal skin in 88.9% (8/9) of the cases, suggesting that vascular network remodeling had occurred in cPN. CONCLUSION: The photoacoustic system has an advantage in noninvasively detecting dermal blood vessel structures that are difficult to recognize by two-dimensional histopathology specimen examination and is worth evaluating in various skin diseases.

Heterotopic ossification of small saphenous vein and panniculitis ossificans of chronic venous insufficiency presenting with livedo racemosa.

OBJECTIVES: Livedo racemosa is a reticulate eruption that presents with branched and partially blanchable incomplete rings. Livedo racemosa is distinct from livedo reticularis, a similar condition that presents with a diffuse and symmetrical blanchable eruption. In contrast to livedo reticularis which may be physiological, livedo racemosa is always associated with an underlying pathology. To our knowledge, this is the first report of panniculitis ossificans and heterotopic ossification of small saphenous vein (SSV) presenting with livedo racemosa. METHODS: We present a 70-year-old male referred for investigation and management of progressive pigmentation and 'lipodermatosclerosis' of lower limbs. There was no history of deep venous thrombosis but an earlier ultrasound had detected a non-occlusive thrombus in the left SSV. Examination and investigations revealed the skin eruption to be livedo racemosa and the associated subcutaneous induration and nodularity to be due to panniculitis ossificans. Biopsy of the SSV demonstrated segmental heterotopic ossification. Duplex ultrasound demonstrated bilateral superficial and deep venous incompetence but no evidence of an acute or chronic venous thrombosis. The patient was diagnosed with heterotopic ossification secondary to venous insufficiency and managed conservatively. CONCLUSION: Livedo racemosa may be an early sign of panniculitis ossificans and its presence should trigger further diagnostic investigations.