26 May 2022: Textbook Updates

We have posted updates of the following topics:

Microbiology & parasitology > Gram negative bacteria > Fusobacterium necrophorum
by Thomas Cotter, D.O., Hasan Samra, M.D.
Topic summary: Gram negative anaerobe; common oropharyngeal pathogen. Most common causal agent of Lemierre syndrome; oropharyngeal infection leads to septic thrombophlebitis of the internal jugular vein. Demographic: previously healthy adolescents and young adults, ages 14 – 24; M:F = 2:1. Trends: dramatic increase of Lemierre syndrome in last several decades. Treatment: Antibiotics – beta lactam agents (penicillins), metronidazole; surgery – debridement and drainage of abscesses.

Penis & scrotum > Dysplasia / carcinoma in situ > Bowenoid papulosis
by Heather Jones, M.D., Liwei Jia, M.D., Ph.D.
Topic summary: Human papillomavirus (HPV) related proliferation of atypical basaloid and koilocytic cells; characteristically involves the anogenital skin and mucosa. Typically presents as solitary or multiple small pink, brown or violaceous papules or plaques on the penis or other sites. Young, sexually active males (on average, late 20s to early 30s). Overall, favorable prognosis, although recurrence is common following conservative treatment. Conservative treatment modalities include carbon dioxide laser vaporization, cryotherapy, electrocoagulation, 5-aminolevulinic acid mediated photodynamic therapy, excisional surgery, 5-fluorouracil and topical imiquimod cream 5%.

Skin nontumor > Infestations > Demodex
by Bethany R. Rohr, M.D., Eric W. Hossler, M.D.
Topic summary: Demodex mites are commensal organisms that are occasionally implicated in inflammatory skin disease. Pathogenic with overgrowth or immune reaction causing rosacea or folliculitis. Prevalence increases with age; M > F. 2 species on humans: D. folliculorum and D. brevis. Possible association with neutrophilic sebaceous adenitis. Treatment: topical sulfur compounds, permethrin, ivermectin, topical metronidazole, topical dilute camphor oil with oral metronidazole, benzyl benzoate (not available in US), lindane, crotamiton, demodectic frost treatment.

Soft tissue > Fibroblastic / myofibroblastic > EWSR1-SMAD3 positive fibroblastic tumor
by Michael Michal, M.D., Ph.D.
Topic summary: Recently characterized, locally aggressive fibroblastic mesenchymal tumor with only 15 cases reported so far. Extremely rare, fusion defined, soft tissue tumor, so far described only on the extremities, with a strong predilection for acral parts. Wide age range (1 – 68 years); M:F = 1:4. Small, painless, infiltratively growing tumor located in the dermis / subcutis. Negative margin status seems to affect the likelihood of recurrence. Complete excision seems to be curative.

Uterus > Other mesenchymal tumors > Perivascular epithelioid cell tumor (PEComa)
by Jennifer A. Bennett, M.D.
Topic summary: Rare mesenchymal neoplasm with myomelanocytic differentiation that is favored to arise from perivascular epithelioid cells. Best classified as a tumor of uncertain malignant potential since recurrences may arise years after initial diagnosis. Most commonly presents at 40 – 60 years (range: 6 – 79). Diagnosis: rarely made on endometrial sampling. Surgery (hysterectomy, myomectomy) is first line therapy as many are presumed leiomyomas. Chemotherapy and radiation may be administered in patients with metastatic or recurrent disease.

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