Ch. 16 - Panniculitis

Question 1

Distinguish between the patterns of septal and lobular panniculitis.

Answer 1

Septal: Normal small uniform fat lobules.

Lobular: Necrotic, enlarged/variable, with lipophages.

Question 2

Erythema nodosum

Answer 2

Septal panniculitis with neutrophils (acute) or granulomatous inflammation (chronic) in septum.

Question 3

What conditions present with lobular panniculitis?

Answer 3

Lupus panniculitis (lupus profundus)

Pancreatic panniculitis

Subcutaneous fat necrosis of the newborn

Eosinophilic panniculitis

Suppurative/granulomatous panniculitis

Nodular vasculitis/erythema induratim of Bazin

Alpha-1 antitrypsin deficiency

Lipodermatosclerosis (stasis paniculitis)

Cytophagic histiocytic panniculitis

Question 4

Lupus panniculitis (lupus profundus)

Answer 4

Lobular panniculitis with fibrin & hyaline rings around fat. Nodular lymphoid infiltrate. Other lupus features…

Question 5

Pancreatic panniculitis

Answer 5

Necrosis of fat lobule with calcium soap outlining necrotic lipocytes. In context of pancreatitis.

Question 6

Subcutaneous fat necrosis of the newborn

Answer 6

Necrosis of fat lobule with crystallization of fat. Granulomatous inflammation.

Question 7

Eosinophilic panniculitis

(causes?)

Answer 7

Eosinophils in septum and lobule with variable necrosis.

(Churg-strauss, parasite, arthropod…)

Question 8

Suppurative and granulomatous panniculitis

Answer 8

Lobular panniculitis with suppurative/granulomatous infiltrate. Usually infectious etiology.

Question 9

Nodular vasculitis / erythema induratum (EI) of Bazin

Answer 9

Necrosis of fat lobule with multinucleated giant cells and nodular neutrophilic vasculitis.

Question 10

Alpha-1 antitrypsin deficiency

Answer 10

Neutrophilic infiltrate with fat necrosis and granulomatous infiltrate.

Question 11

Lipodermatosclerosis (stasis panniculitis)

Answer 11

Necrosis of the fat lobule with lipomembranous change and overlying stasis change.

Question 12

Cytophagic histiocytic panniculitis

Answer 12

Lobular panniculitis with “beanbag cells”, actually histiocytes that have engulfed inflammatory cells and erythrocytes.

Question 13

Traumatic fat necrosis (“mobile encapsulated lipoma”)

Answer 13

Fat necrosis resembling lobular panniculitis with a fibrous capsule.

Question 14

Subcutaneous panniculitis-like lymphoma

Answer 14

Resembles lobular panniculitis (especially lupus) but with atypical lymphocytes rimming lipocytes.

Question 15

Answer 15

Septal panniculitis

Answer 16

Lobular panniculitis

Question 17

Answer 17

Erythema nodosum

Question 18

Answer 18

Lupus panniculitis (lupus profundum)

Question 19

Answer 19

Pancreatic panniculitis

Question 20

Answer 20

Subcutaneous fat necrosis of the newborn

Question 21

Answer 21

Eosinophilic panniculitis

Question 22

Answer 22

Nodular vasculitis / erythema induratum

Question 23

Answer 23

Alpha-1 antitrypsin deficiency

Question 24

Answer 24

Lipodermatosclerosis

Question 25

Answer 25

Cytophagic histiocytic panniculitis

Question 26

Answer 26

Subcutaneous panniculitis-like lymphoma