Panniculitis - 脂肪織炎https://en.wikipedia.org/wiki/Panniculitis
脂肪織炎 (Panniculitis) は、皮下脂肪組織の炎症を特徴とする疾患群です。症状には、皮膚の圧痛結節や、体重減少や​​疲労などの全身症状が含まれます。

「結節性紅斑」は、発熱、倦怠感、関節痛などの全身症状を伴う、1 ~ 10 cm の圧痛のある赤い結節を特徴とする 脂肪織炎 (panniculitis) の一種です。小結節は、潰瘍化や瘢痕化することなく 2 ~ 6 週間で治まる場合があります。結節性紅斑は、C型肝炎、EBV、結核などの感染症、妊娠、非ホジキンリンパ腫、膵臓がんなどに関連しています。

  • 結核は重大な原因の 1 つです。
  • 脚は一般的に影響を受ける部位です。
References Erythema Nodosum: A Practical Approach and Diagnostic Algorithm 33683567 
NIH
Erythema nodosum is the most common form of panniculitis and is characterized by tender erythematous nodules mainly in the lower limbs on the pretibial area. The exact cause of erythema nodosum is unknown, although it appears to be a hypersensitivity response to a variety of antigenic stimuli. Although the etiology is mostly idiopathic, ruling out an underlying disease is imperative before diagnosing primary erythema nodosum. Erythema nodosum can be the first sign of a systemic disease that is triggered by a large group of processes, such as infections, inflammatory diseases, neoplasia, and/or drugs. The most common identifiable causes are streptococcal infections, primary tuberculosis, sarcoidosis, Behçet disease, inflammatory bowel disease, drugs, and pregnancy.
 Panniculitis in Children 34449587 
NIH
Panniculitis は、皮下脂肪組織が関与する炎症性疾患の異種グループを形成します。これらの障害は小児ではまれです。脂肪織炎は、全身性疾患の一次プロセスである場合もあれば、感染、外傷、薬剤への曝露に起因する二次プロセスである場合もあります。ほとんどのタイプの脂肪織炎は、(病因に関係なく)同じ臨床像を示し、圧痛のある紅斑性の皮下結節を伴います。
Panniculitides form a heterogenous group of inflammatory diseases that involve the subcutaneous adipose tissue. These disorders are rare in children and have many aetiologies. As in adults, the panniculitis can be the primary process in a systemic disorder or a secondary process that results from infection, trauma or exposure to medication. Some types of panniculitis are seen more commonly or exclusively in children, and several new entities have been described in recent years. Most types of panniculitis have the same clinical presentation (regardless of the aetiology), with tender, erythematous subcutaneous nodules.
 Erythema nodosum - a review of an uncommon panniculitis 24746312
Panniculitis 、皮下脂肪の炎症は、通常、炎症性結節を伴います。 Erythema nodosum (EN) は臨床的に最も頻度の高い脂肪織炎です。 EN の最大 55% は特発性であると考えられていますが、最も一般的な原因には、感染症、薬物、サルコイドーシスや炎症性腸疾患などの全身疾患、妊娠、悪性腫瘍が含まれます。 EN は通常 10 代と 20 代に発症し、女性に多く見られます。多くの場合、発熱、倦怠感、上気道感染症の症状などを伴う 1 ~ 3 週間の非特異的前駆症状が続きます。その後、皮膚病変が続き、通常は四肢の伸筋面に局在します。病変は、痛みを伴う円形または楕円形の、わずかに隆起した潰瘍性のない赤い結節です。 EN の正確な病因は不明ですが、皮下脂肪の中隔細静脈における免疫複合体の沈着が原因で好中球性脂肪織炎を引き起こすと考えられています。原因となる症状に対する特別な治療がなくても、ほとんどの場合、EN は治療なしで治癒します。
Panniculitis, inflammation of the subcutaneous fat, usually presents with inflammatory nodules. Erythema nodosum (EN) is clinically the most frequent form of panniculitis. Whilst up to 55% of EN is considered idiopathic, the most common causes include infections, drugs, systemic illnesses such as sarcoidosis and inflammatory bowel disease, pregnancy, and malignancy. EN typically presents in the teens and 20s, and is seen more commonly in females. It is often preceded by a non-specific prodrome of one to three weeks, which may include fever, malaise, and symptoms of an upper respiratory tract infection. Cutaneous lesions then follow, typically localized on the extensor aspect of the limbs. The lesions are painful rounded or oval, slightly raised, non-ulcerative red nodules. The exact pathogenesis of EN is not understood, although is thought to result from deposition of immune complexes in the venules of the septae in subcutaneous fat, causing a neutrophilic panniculitis. Even without specific therapy for a causative condition, EN resolves without treatment in most cases.