5/23/2017. Disclosure of Relevant Financial Relationships. Flank mass in a 43-year-old male. History. Bobbi S. Pritt, MD, MSc Mayo Clinic

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1 Flank mass in a 43-year-old male Bobbi S. Pritt, MD, MSc Mayo Clinic Disclosure of Relevant Financial Relationships USCAP requires that all faculty in a position to influence or control the content of CME disclose any relevant financial relationship WITH COMMERCIAL INTERESTS which they or their spouse/partner have, or have had, within the past 12 months, which relates to the content of this educational activity and creates a conflict of interest. Dr. Bobbi Pritt declares she has no conflicts of interest to disclose. History 43 year old male presented with tender plaques and nodules involving his left flank. Patient is from the upper Midwestern United States No travel outside of the United States. His previous medical history is significant for well-controlled insulin-dependent diabetes. An excisional biopsy was performed of one of the nodules H&E, 20x total magnification H&E, 40x total magnification H&E, 100x total magnification H&E, 200x total magnification 1

2 H&E, 100x total magnification H&E, 100x total magnification H&E, 100x total magnification Masson s Trichrome, 40x total magnification Diagnosis? A. Helminth, possible roundworm. B. Helminth, possible cestode C. Not a helminth, foreign body D. Not a helminth, fat necrosis E. No idea, (ask a colleague!) Masson s Trichrome, 100x total magnification 2

3 Lipomembranous Fat Necrosis - General A.k.a. membranocystic fat necrosis, lipomembranous panniculitis Initially described in 1974 in bone and subcutaneous tissues in a case of sudanophilic leukodystrophy of cerebral hemispheres Commonly observed in association with venous insufficiency, arterial ischemia, diabetes, erythema nodosum, and lupus Degenerative process involving mature adipose tissue Described from various sites: subcutaneous tissue (usually lower extremities), breast, testicle, bone marrow, benign and malignant tumors Observed in 0.7% to 9% of inflammatory lesions of subcutaneous tissues More common in women (89% in one case series: Snow et al.) Mean age 57 years (range years) Lipomembranous Fat Necrosis - Morphology Cystic (most common; often microcystic) and non-cystic forms Adipocyte necrosis Formation of eosinophilic anucleate, crenated, undulating ribbon-like membranes. Pseudopapillary tufts PAS-positive, diastase resistant membranes CD68 and lysozyme positive Cysts may form complex Arabesque patterns Polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy (courtesy of Dr. Andrew Folpe) Autosomal recessive genetic disorder Associated with polymorphisms of 2 genes: TYROBP (DAP12) and TREM2 Characterized by fractures (resulting from polycystic osseous lesions), frontal lobe syndrome, and progressive pre-senile dementia beginning in the fourth decade. Patient: 34 year-old female residing in a skilled nursing facility. Presented with fractures of the tibia and other bones. Image courtesy of Lawrence Gibson, MD 3

4 Large Worms in Subcutaneous Tissue DDX: Worms in Tissue Roundworms Dirofilaria species (size in cross-section: µm) Onchocerca volvulus ( µm diameter) Loa loa (~500 µm in diameter) Tapeworms Taenia solium (cysticercosis) Other Taenia sp. (coenurosis) Spirometra sp. (sparganosis) Anatomy of a Roundworm Examples of large roundworms Zoonotic Onchocerca species Dirofilaria species Cuticle (including spines, ridges) Well-defined musculature Internal organs Image by Lars Westblade, PhD Image by Ryan Relich, PhD 4

5 Anatomy of a tapeworm larva Thin acellular cuticle Smooth muscle fibers Calcareous corpuscles (small calcified bodies) Depending on the tapeworm: protoscoleces (immature heads) with suckers and hooklets, fluidfilled sac A recent case of lipomembranous fat necrosis simulating a cestode. Lipomembranous fat necrosis Sparganosis Other examples of tapeworm larvae A recent case of cysticercosis Image by Paul Valenstein, MD 5

6 DDx: plant material 4 mm 1 mm Look for defined structures Cuticle and underlying musculature LM fat necrosis No well-defined cuticle (external lining merges with underlying fibrous connective tissue Look for defined structures Cuticle and underlying musculature Reproductive or gastrointestinal organs Eggs (requires familiarity) Round worm Look for defined structures Cuticle and underlying musculature Reproductive or gastrointestinal organs Eggs (requires familiarity) Special stains Masson s trichrome, PAS, acid fast Polarizable? Consult (e.g. microbiologist, colleague, CDC ID Path and DPDx groups) References Nasu et al. A lipid metabolic disease membranous lip dystrophy an autopsy case demonstrating numerous peculiar membrane-structures composed of compound lipid in bone and bone marrow and various adipose tissues. Acta Pathol Jpn 1973;23: Segura S, Pujol RM. Lipomembranous fat necrosis of the subcutaneous tissue. Dermatol Clin 2008;26: Snow JL, Su WPD. Lipomembranous (membranocystic) fat necrosis: clinicopathologic correlation of 38 cases. Am J Dermatopathol 1996;18(2): Diaz-Cascajo C, Borghi S. Subcutaneous pseudomembranous fat necrosis: new observations. J Cutan Pathol 2002;29:5-10. Pritt BS, Elhosseiny A. Artifacts and pitfalls in infectious disease pathology. In Pathology of Infectious Diseases, Procop GW and Pritt BS (Eds) Elsevier: Philadelphia, PA 6

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