A patient presents with the skin lesion shown in the image. The characteristic net-like, violaceous discoloration is most consistent with which of the following diagnoses?

Question

Accepted Answer

B. Livedo reticularis. ## Image Findings
*   A widespread, net-like (reticulated) pattern of bluish-red (violaceous) discoloration on the skin of a limb.
*   The discoloration forms irregular, branching, and interconnected rings or patches.
*   The central areas within the "net" appear relatively paler or normal skin colored.
*   No significant elevation, scaling, blistering, or ulceration is evident.

## Diagnosis
**Key Point:** The image demonstrates a classic **livedo reticularis**, characterized by a persistent, reticulated, bluish-red vascular pattern on the skin.

Livedo reticularis is a common cutaneous manifestation resulting from impaired blood flow in the dermal capillaries and venules. This leads to deoxygenated blood pooling, creating the characteristic net-like, mottled appearance. It can be physiological (cutis marmorata, often transient with cold exposure) or pathological, associated with various underlying conditions affecting vascular integrity or blood viscosity.

## Clinical Relevance
**Clinical Pearl:** While often benign and physiological (especially in response to cold), persistent or extensive livedo reticularis, particularly if associated with ulceration or pain, warrants investigation for underlying systemic diseases such as autoimmune disorders (e.g., SLE, antiphospholipid syndrome), vasculitis, cryoglobulinemia, or hypercoagulable states.

## High-Yield for NEET PG
**High-Yield:** Livedo reticularis is a key dermatological sign that can indicate systemic disease, especially when it is fixed, painful, or associated with ulceration.
**Key Point:** The term "livedo racemosa" refers to a more irregular, broken, and widespread form of livedo reticularis, which is almost always pathological and often associated with vasculitis or thrombotic disorders.

## Common Traps
**Warning:** Do not confuse physiological livedo reticularis (cutis marmorata) with pathological forms. Physiological livedo is transient and resolves with warming, whereas pathological forms are persistent and may be associated with other symptoms.

## Reference
[cite:Robbins & Cotran Pathologic Basis of Disease, Ch 11; Harrison's Principles of Internal Medicine, Ch 62]

Answer

A. Erythema nodosum

Answer

C. Cellulitis

Answer

D. Urticaria

A patient presents with the skin lesion shown in the image. The characteristic net-like, violaceous discoloration is most consistent with which of the following diagnoses?

Explanation

Image Findings

Diagnosis

Differential Diagnosis

Clinical Relevance

High-Yield for NEET PG

Common Traps

Reference

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Feature	Livedo Reticularis	Erythema Nodosum	Urticaria	Cellulitis
Appearance	Net-like, violaceous, mottled vascular pattern	Tender, erythematous subcutaneous nodules	Transient, itchy wheals with central pallor	Diffuse, spreading erythema, warmth, swelling
Palpation	Non-palpable (unless associated with vasculitis)	Palpable, tender nodules	Palpable, raised wheals	Warm, tender, indurated
Distribution	Often limbs, trunk	Typically shins	Anywhere, often trunk and extremities	Anywhere, often lower extremities
Duration	Persistent or transient	Weeks to months	Hours (individual lesions)	Days to weeks