Panniculitis. Nathan C. Walk

Pannic litisPannic litisPanniculitisPanniculitisNathan C. Walk, M.D.Nathan C. Walk, M.D.

Normal morphology of subcutaneous fatNormal morphology of subcutaneous fatNormal morphology of subcutaneous fatNormal morphology of subcutaneous fat

SubSub--Q fat has a limited repertoire of responses toQ fat has a limited repertoire of responses toSubSub Q fat has a limited repertoire of responses to Q fat has a limited repertoire of responses to noxious stimulinoxious stimuli–– Fat necrosis Fat necrosis

V i fV i fVarious forms:Various forms:–– Enzymatic, crystalline, suppurative, hyalinizing, microcysticEnzymatic, crystalline, suppurative, hyalinizing, microcystic–– LIPOPHAGIC LIPOPHAGIC –– most common, least specificmost common, least specific

Fat often involved secondarily in another primary processFat often involved secondarily in another primary process–– Fat often involved secondarily in another primary processFat often involved secondarily in another primary processVasculitisVasculitisDeep fungalDeep fungalR di tiR di tiRadiationRadiationTraumaTraumametastaticmetastatic

C id bl l !!C id bl l !!–– Considerable overlap!!Considerable overlap!!

Stages of lesionStages of lesiongg–– Neutrophils first….Neutrophils first….–– Lymphocytes with giant cells and lipidLymphocytes with giant cells and lipid--containing macrophagescontaining macrophages

FibrosisFibrosis–– FibrosisFibrosis

Adequate biopsy is the keyAdequate biopsy is the key

PanniculitisPanniculitisSeptal panniculitis (Venous disorders)Septal panniculitis (Venous disorders)–– Erythema nodosumErythema nodosum–– Necrobiosis lipoidicaNecrobiosis lipoidicapp–– SclerodermaScleroderma

Lobular panniculitis (Arterial supply disruption)Lobular panniculitis (Arterial supply disruption)–– Subcutaneous fat necrosis of the newbornSubcutaneous fat necrosis of the newbornSubcutaneous fat necrosis of the newbornSubcutaneous fat necrosis of the newborn–– Sclerema neonatorumSclerema neonatorum–– WeberWeber--Christian diseaseChristian disease–– Alpha 1Alpha 1--antitrypsin deficiencyantitrypsin deficiencyAlpha 1Alpha 1--antitrypsin deficiencyantitrypsin deficiency–– Cytophagic histiocytic panniculitisCytophagic histiocytic panniculitis–– PanniculitisPanniculitis--like Tlike T--cell lymphomacell lymphoma

Pancreatic panniculitisPancreatic panniculitis–– Pancreatic panniculitisPancreatic panniculitis–– Lupus panniculitisLupus panniculitis

Panniculitis associated with large vessel vasculitisPanniculitis associated with large vessel vasculitisl dl d–– Cutaneous polyarteritis nodosaCutaneous polyarteritis nodosa

–– Superficial migratory thrombophlebitisSuperficial migratory thrombophlebitis

Case 129Case 129Case 129Case 129

Lupus profundusLupus profundusLupus profundusLupus profundus½ of cases have epidermal and dermal changes of LE½ of cases have epidermal and dermal changes of LE–– ?Which are…..?Which are…..

Lobular panniculitis with prominent lymphocytic infiltrateLobular panniculitis with prominent lymphocytic infiltrateLobular panniculitis with prominent lymphocytic infiltrateLobular panniculitis with prominent lymphocytic infiltrate–– Characteristic feature: Characteristic feature: paraseptal lymphoid follicles, sometimes with paraseptal lymphoid follicles, sometimes with

germinal centergerminal centerUncommon in other panniculitidesUncommon in other panniculitides

Late lesions with dystrophic calcificationLate lesions with dystrophic calcification

Cas130Cas130Cas130Cas130

ParaffinomaParaffinomak S l i li lk S l i li laka…Sclerosing lipogranulomaaka…Sclerosing lipogranuloma

Special form of facticial panniculitis resulting from injection of lipi Special form of facticial panniculitis resulting from injection of lipi (often paraffin) into subcutaneous tissue(often paraffin) into subcutaneous tissue

Well circumscribed noduleWell circumscribed nodulee c cu sc bed odu ee c cu sc bed odu e? Swiss cheese appearance? Swiss cheese appearanceBands of hyaline fibrous tissue between fat cells and cystic spacesBands of hyaline fibrous tissue between fat cells and cystic spaces

Case 131Case 131Case 131Case 131

Lobular panniculitis, c/w Erythema Lobular panniculitis, c/w Erythema i di dinduratuminduratum

In lobular panniculitides, inflammatory infiltrate is In lobular panniculitides, inflammatory infiltrate is t th h t th l b l BUT th i ftt th h t th l b l BUT th i ftpresent throughout the lobule…BUT, there is often some present throughout the lobule…BUT, there is often some

septal involvement as well.septal involvement as well.

Nodular vasculitis/Erythema induratumNodular vasculitis/Erythema induratum–– Originally 1 entity, then 2 (Bazin, Whitfield), now one again?Originally 1 entity, then 2 (Bazin, Whitfield), now one again?–– Appears to be a disease of diverse etiologiesAppears to be a disease of diverse etiologies

Lobular or septolobular panniculitis… with:Lobular or septolobular panniculitis… with:–– Granulomatous inflammation Granulomatous inflammation –– usually poorly developed, ALSO usually poorly developed, ALSO

with neutrophils lymphocytes and some plasma cellswith neutrophils lymphocytes and some plasma cellswith neutrophils, lymphocytes, and some plasma cellswith neutrophils, lymphocytes, and some plasma cells–– VasculitisVasculitis–– NecrosisNecrosis–– Septal fibrosisSeptal fibrosis–– Septal fibrosisSeptal fibrosis

Case 132Case 132Case 132Case 132

LipodystrophyLipodystrophyLipodystrophyLipodystrophyLipoatrophyLipoatrophyp p yp p y–– Primary, idiopathic = lipodystrophyPrimary, idiopathic = lipodystrophy–– SecondarySecondary

Follows other panniculitides (lupus, morphea, )Follows other panniculitides (lupus, morphea, )Follows other panniculitides (lupus, morphea, …)Follows other panniculitides (lupus, morphea, …)Looks the same histologicallyLooks the same histologically

InIn established casesestablished cases –– atrophy of fat withOUTatrophy of fat withOUTIn In established casesestablished cases atrophy of fat withOUT atrophy of fat withOUT inflammationinflammation–– Involutional changes… small lipocytes and intervening Involutional changes… small lipocytes and intervening

hyaline or myxoid connective tissuehyaline or myxoid connective tissuehyaline or myxoid connective tissuehyaline or myxoid connective tissueEarly or “active” lesions may have lobular Early or “active” lesions may have lobular panniculitis w/ foam cells, small fat cystspanniculitis w/ foam cells, small fat cysts

Case 133Case 133Case 133Case 133

Pancreatic panniculitisPancreatic panniculitisPancreatic panniculitisPancreatic panniculitis

Lobular panniculitisLobular panniculitisLobular panniculitisLobular panniculitisEnzymatic fat necrosisEnzymatic fat necrosis

Li f ti ith b kd f f t llLi f ti ith b kd f f t ll–– Liquefaction with breakdown of fat cellsLiquefaction with breakdown of fat cellsGhostGhost--like outline of fat cells remaininglike outline of fat cells remaining

At margins of necrotic fat:At margins of necrotic fat:–– At margins of necrotic fat:At margins of necrotic fat:Variable neutrophils, nuclear dusting, fine Variable neutrophils, nuclear dusting, fine basophilic calcium deposits, hemorrhagebasophilic calcium deposits, hemorrhagebasophilic calcium deposits, hemorrhagebasophilic calcium deposits, hemorrhage

Case 134Case 134Case 134Case 134

Septal panniculitis, c/w Erythema Septal panniculitis, c/w Erythema ddNodosumNodosum

Septal panniculitisSeptal panniculitis–– Mostly lymphocytes, variable numbers of giant cellsMostly lymphocytes, variable numbers of giant cells–– Center of lobule sparedCenter of lobule spared

Early lesions Early lesions –– more neutrophilsmore neutrophilsLater lesions Later lesions –– more fibrosis, septal thickeningmore fibrosis, septal thickening

Case 135Case 135Case 135Case 135

Calcifying panniculitisCalcifying panniculitisCalcifying panniculitisCalcifying panniculitisCalciphylaxisCalciphylaxis

R lifR lif th t i dth t i d–– Rare, lifeRare, life--threatening syndromethreatening syndrome–– Progressive microvascular and superficial soft tissue calcificationProgressive microvascular and superficial soft tissue calcification–– Setting of secondary hyperparathyroidism and chronic renal failureSetting of secondary hyperparathyroidism and chronic renal failure

–– Painful violaceous skin lesions that progress to nonhealing ulcers with Painful violaceous skin lesions that progress to nonhealing ulcers with underlying tissue necrosisunderlying tissue necrosis

–– Many complications…mortality >60%Many complications…mortality >60%

–– Histology:Histology:Intravascular calcium deposits within small and mediumIntravascular calcium deposits within small and medium--sized vesselssized vesselsAlso within extravascular soft tissues and visceraAlso within extravascular soft tissues and visceraMay have endovascular fibroblasticMay have endovascular fibroblastic intimal proliferation luminal thrombosisintimal proliferation luminal thrombosisMay have endovascular fibroblasticMay have endovascular fibroblastic--intimal proliferation, luminal thrombosis, intimal proliferation, luminal thrombosis, or calcific obliteration of vesselsor calcific obliteration of vessels“Clean” necrosis“Clean” necrosis

–– Relatively Relatively scantscant inflammationinflammation

“Calcifying panniculitis”“Calcifying panniculitis”y g py g p–– A number of other conditions may imitate calciphylaxis A number of other conditions may imitate calciphylaxis

histopathologically histopathologically –– diagnosis requires careful integration of diagnosis requires careful integration of clinical and pathologic informationclinical and pathologic information

Peripheral vascular diseasePeripheral vascular diseaseAtheroembolus syndromeAtheroembolus syndromeSeptic embolismSeptic embolismDermatomyositisDermatomyositisDermatomyositisDermatomyositisMixed CTDMixed CTDAntiphospholipid antibody syndromeAntiphospholipid antibody syndromeDICDICDICDICPyoderma gangrenosumPyoderma gangrenosumLipodermatosclerosisLipodermatosclerosis….….

Case 136Case 136Case 136Case 136

Subcutaneous fat necrosis of the Subcutaneous fat necrosis of the bbnewbornnewborn

Normal epidermis and dermis with anNormal epidermis and dermis with anNormal epidermis and dermis with an Normal epidermis and dermis with an underlying lobular panniculitisunderlying lobular panniculitis–– Mixed inflammatory infiltrateMixed inflammatory infiltrateyyMany fat cells retain their outlineMany fat cells retain their outline–– Narrow clefts radiate from periphery of cellNarrow clefts radiate from periphery of cellNarrow clefts radiate from periphery of cellNarrow clefts radiate from periphery of cell

Contain doubly refractile needleContain doubly refractile needle--like crystalslike crystals

Same histology as Sclerema neonatorumSame histology as Sclerema neonatorum–– Except, SN has less inflammationExcept, SN has less inflammation

Case 137Case 137Case 137Case 137

LipodermatosclerosisLipodermatosclerosisLipodermatosclerosisLipodermatosclerosis

Synonyms:Synonyms:Synonyms: Synonyms: –– Membranous lipodystrophyMembranous lipodystrophy–– Sclerosing PanniculitisSclerosing Panniculitisgg

Histology:Histology:–– Stasis changes at topStasis changes at top–– Septal fibrosis Septal fibrosis –– THICK septaTHICK septa–– Fatty microcysts with “membranocystic change”Fatty microcysts with “membranocystic change”

Feathery cuticle inside cyst Feathery cuticle inside cyst –– “arabesque pattern”“arabesque pattern”

Case 138Case 138Case 138Case 138

Granulomatous panniculitisGranulomatous panniculitisGranulomatous panniculitisGranulomatous panniculitis–– AFB, GMS, Gram all negativeAFB, GMS, Gram all negative

–– Secondary to:Secondary to:TraumaTraumaTraumaTraumaInfectionInfection…..?…..?…..?…..?