Overlap of histological features of pigmented purpuric dermatosis and kaposi sarcoma – pseudo kaposi sarcoma

Introduction

Pseudo-Kaposi sarcoma is an extremely rare usually self-limiting disease. Can be congenital or acquired. Although etiology remains unknown, due to prolong venous stasis along with insufficiency of the calf muscle to pump the capillaries leads to chronic edema resulting in chronic tissue hypoxemia and induces new vessels and fibroblast proliferation.

Case

A 14-year-old boy presented with right lower limb multiple erythematous to slightly vascular plaque since 6 months. He complains of mild to moderate swelling in the right lower limb on prolong standing subsides after taking rest. On cutaneous examination, lateral aspect of the lower half of right leg shows discrete erythematous to slightly purpuric ill-defined barely elevated plaques [Figure 1] measuring from smallest of 1x1 cm and largest being 3x6 cm, of which a plaque shows white to yellow crusting slight verrucous surface [Figure 2]. No local rise of temperature, nor tenderness, thrill, compressibility. No ulceration, no palpable pulsation. No hypertrophy of limbs, or spinal deformity. While examining we found soft compressible skin-colored swelling suggestive of incompetent perforators on prolonged standing. Brodie- Trendelenburg test for SFJ was normal, for perforators were positive. A differential diagnosis of pseudo-Kaposi sarcoma, verrucous hemangioma, angiokeratoma circumscriptum. Advised for Venous doppler of right lower limb which shows competent saphanofenoral, saphenopopliteal perforators, prominent GSV, multiple focal incompetent perforators, and varicosities with hard nodular subcutaneous fat suggestive of venous malformation secondary to incompetent perforators. Dermoscopy shows radial vascular streaks in pink to erythematous background which blanches on pressure [Figure 3]. Biopsy from two sites taken which shows hyperkeratosis with focal acanthosis [Figure 4], superficial and mid dermis shows multiple small dilated capillaries lined with plump endothelial cells [Figure 5], perivascular lymphocytic cells, and extravasated RBCs suggestive of Acroangiodermatitis of mali (PseudoKaposi sarcoma).

We prescribed topical timolol, calcium dobesilate, limb elevation, and compression therapy. The lesion showed a slight decrease in size and vascularity after 2-3 weeks of follow-up [Figure 6].

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Discussion

Pseudo-Kaposi sarcoma is an extremely rare usually self-limiting disease. Earhart et al. used the term pseudo-Kaposi sarcoma in 1974 for the first time, 1 later the same clinical picture was introduced by Mali in 1965 as kaposiform skin lesion, in chronic vascular insufficiency patients. Causes can be congenital or acquired (as in our case). Presents as brown to hyperpigmented macules, purplish plaque, violaceous nodules which progresses to become verrucous later ulcerates. Pseudo-Kaposi sarcoma seen in chronic venous incompetency,2 paresis of extremities,3 amputation stump, 4 procedures such as arteriovenous fistula for hemodialysis, 5 and suction-socket lower limb prosthesis, 6 following minor trauma. 7 Differentiating features of pseudo Kaposi sarcoma and Kaposi sarcoma is summarized in Table 1.

Various variants of acroangiodermatitis are:

Although etiology remains unknown, due to prolong venous stasis along with insufficiency of the calf muscle to pump the capillaries leading to chronic edema resulting in chronic tissue hypoxemia induces new vessel and fibroblast proliferation.10

Management of acroangiodermatitis is correction of underlying pathology, such as chronic venous insufficiency which includes, graded compression stockings, compression pump for venous stasis and local antibiotic treatment and regular wound care in case of venous ulcers. For gravitational eczema topical corticosteroids is included.9 Oral erythromycin 500mg QID and oral Dapsone 50mg BD for 3months showed best results.11 Pulsed dye laser can be considered for therapy. In arteriovenous malformation embolization of small fistulae, surgical elimination of shunts can be considered. 12

Conclusion

Our patient has Mali type of variant with atypical presentation with younger age of onset, presenting unilateral limb on both medial and lateral aspect as lichenified keratotic palque which usually get under diagnosed.

Source of Funding

None.

Conflict of Interest

None.