12 May 2022: Textbook Updates

We have posted updates of the following topics:

Bone & joints > Other nonneoplastic > Epidermoid inclusion cyst
by Alnoor Akber, M.D., Nasir Ud Din, M.B.B.S.
Topic summary: Benign epithelial inclusion cyst in the bone lined with stratified squamous epithelium, identical to cutaneous counterpart. Post traumatic squamous epithelium embedded in bone. Rare incidence, young to middle aged. Common in the acral skeleton (fingers and toes) and skull. Asymptomatic / painless lump. Clinical, radiological and pathological correlation is adequate for diagnosis. Excellent prognosis. Treatment: simple curettage or excision.

Oral cavity & oropharynx > Other nonneoplastic > Amalgam tattoo
by Sarah H. Glass, D.D.S.
Topic summary: Iatrogenic implantation of exogenous foreign material, specifically dental amalgam, into the tissues of the oral cavity. Gray, blue or black macule on clinical exam in the oral cavity. Affects 3.3% of the U.S. adult population. Occurs in any location in the oral cavity, with gingiva and alveolar mucosa being the most common location due to proximity to the teeth. Excellent prognosis. No treatment is needed once diagnosis is established.

Skin nontumor > Dermal perivascular and vasculopathic reaction patterns > Erythema annulare centrifugum
by M. Suzanne Bloomquist, M.D., Silvija P. Gottesman, M.D.
Topic summary: Annular, erythematous, well circumscribed, mildly pruritic eruption with classic trailing scale (scale is seen behind the advancing erythematous edge). Clinicopathologic correlation is necessary, since the superficial variant may be indistinguishable from pityriasis rosea. Incidence: 1 per 100,000. One study showed that the superficial type may show shorter duration of skin lesion and better response to therapy but may have higher rate of recurrence. Typically, any treatment is directed at symptom relief, including topical corticosteroids and antihistamines for pruritic lesions.

Soft tissue > Adipose tissue tumors > Liposarcoma > Pleomorphic liposarcoma
by Stacy D. Webb, M.D., David Suster, M.D.
Topic summary: Pleomorphic, high grade sarcoma with variable numbers of pleomorphic lipoblasts, without areas that resemble atypical lipomatous tumor / well differentiated liposarcoma (or other lines of differentiation) and absence of MDM2 gene alterations by cytogenetic and molecular studies. M > F. 66% of cases occur on the extremities (lower limbs > upper). Aggressive, often exhibiting local recurrence and metastatic rates of 30 – 50%. Wide or radical resection with negative margins or amputation with postoperative radiotherapy; also chemotherapy.

Stains & CD markers > PAX5
by Austin Ellis, M.D., Ling Zhang, M.D.
Topic summary: 1 of 9 paired box transcription factors; involved in the differentiation and maturation of lymphoid progenitor cells into B cells, development of the nervous system and spermatogenesis. Nuclear marker expressed in most mature and immature B cell neoplasms. Activates B cell specific genes and represses genes specific for other hematopoietic lineages. Used to determine B cell lineage in lymphomas that lack CD20 expression. Expression may be associated with aggressive clinical course in olfactory neuroblastoma.

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