Thursday, November 29, 9pm EST
Book discussed: WHO Classification of Skin Tumours
Special Guests: Dr Richard A. Scolyer (@ProfRScolyerMIA) and Dr Rajendra Sing (@mydermpath)
Summary prepared by Abha Soni, DO, MPH (@AsoniDO)
Journal Club Summary:
Topics Discussed:
Variants of cutaneous SCC:
-
- Squamous cell carcinoma (NOS)
- Keratoacanthoma*
- Verrucous SCC*
- Acantholytic SCC
- Adenosquamous SCC
- Spindle cell SCC
- Rare variants (Lymphoepithelial-like SCC, Pseudovascular SCC, and SCC with sarcomatoid differentiation)
*These low-grade variants can be locally destructive but have little potential to metastasize
Basal Cell Carcinoma:
- Lower Risk: Superficial, nodular, pigmented, infundibulocystic, Fibroepithelioma of Pinkus
- Fibroedpitheloma of Pinkus, aka Pinkus tumor renamed as fibroepithelial basal cell carcinoma
- Higher Risk: Micronodular, infiltrating, morpheaform/sclerosing, basosquamous carcinoma, BCC with sarcomatoid differentiation
- Micronodular: irregular, infiltrative deep/peripheral edges. Defined as >50 small nodules (<0.15 mm in diameter)
- Infiltrating: Small irregular/jagged nests, at least 5-8 cells thick at least
- In contrast, Dr. Singh explained that morpheaform can be less than 5 cells thick. “In short, morpheaform tends to have smaller basaloid nests. But to stress again many consider them as same of overlapping features.”
- Others commented that in the morpheaform subtype they also look for dense fibrous/keloid-like collagen fibers
Basosquamous: Zones contain cells with intermediate features between the two. The basaloid component stains positive for BerEP4 and the squamous areas express MUC1 (EMA)
Melanocytic Tumors:
- This new approach to melanoma classification was appreciated by many in the Dermpath JC twitter community as there is a higher emphasis on the chronicity of sun damage and how it impacts certain pathways in melanoma progression.
- Two main pathways CDKN2A pathway and the MAPK pathway were discussed.
Dysplastic Nevi:
Low Grade: Moderate cytologic and architectural atypia
High Grade: Severe cytologic and architectural atypia
BAPOMA: Combined nevus with a benign nevic component and almost a spitzoid component. Some spitz like areas show multinucleation with an admixed infiltrate.
BAP1 lost especially present in the larger cells. BRAF mutations mostly also seen.
New Entities:
- Endocrine mucin producing sweat gland carcinoma
- Low-grade neuroendocrine neoplasm
- Predilection for eyelid and periorbital skin. However, occurrence in an extrafacial location has also been reported.
- Precursor of mucinous carcinoma
- Older individuals (i.e. in the sixth and seventh decades of life)
- Positive for CK7, CK8, CK18, AE1/AE3, CAM5.2, EMA, GCDFP15, WT1, ER and PR. Intensity for chromogranin and synaptophysin varies. Ki-67 is low.
- Squamoid eccrine ductal carcinoma
- Present as large nodules and plaques in the head and neck area.
- Positive for cytokeratin and ductal differentiation can be confirmed by MUC1 and CEA.
- Secretory carcinoma of the skin
- Axillary location.
- Rare sites include the face (including the lips), trunk, and limbs.
- Signet ring cell/histiocytoid carcinoma
- Males>females
- Predilection for eyelids, but identical neoplasms have been reported in the axilla.
- Hematolymphoid tumors
- CD30 lymphoproliferative disorders
- Types A-C morphologic criteria remain the same.
- Type D: shows epidermotropic infiltrates of CD8+ and CD30+ atypical cells and mimics primary cutaneous aggressive epidermotropic CD8+ cytotoxic T-cell lymphoma.
- Type E: characterized by angiocentric and destructive infiltrates, predominantly medium sized atypical CD30+ lymphocytes with extensive dermal necrosis and ulceration.
- Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder
- Solitary skin lesion, and no evidence of the patches or plaques.
- Ulcer/papules show spontaneous regression.
- Expression of PD-1(follicular T-cell marker), monoclonality of T-cell receptor (60%).
- Similar phenotype has been observed in patients with multiple lesions. This is still an understudied area and it is important to recognize for therapeutic options and to determine prognosis.
- CD30 lymphoproliferative disorders
Soft tissue tumors:
- New Entities
- Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma
- Spindled to epithelioid, rarely metastasizing neoplasm
- Mimics myotid tumor or epithelioid sarcoma
- SEPINE1-FOSB fusion
- Male predominance
- Lower extremities > upper extremities or trunk
- FOSB consistently positive
- Cutaneous leiomyosarcoma
- Prognosis of these tumors is superb, no metastases
- Grading is not of prognostic value
- Angiosarcoma
- Majority associated with radiation or preexisting lymphedema are associated with MYC gene amplification and co-amplification of FLT-4.
- This may be helpful in cases where MYC amplification is not seen.
- Pseudomyogenic (epithelioid sarcoma-like) hemangioendothelioma
Special thanks to Dr. Singh (@mydermpath) for putting the presentation together and to the @DermpathJC twitter community for another successful discussion.
The detailed slides/summary and accompanying virtual images can be accessed here:
Pathpresenter.net
Login: pp@gmail.com
Password: welcomepp
Click on: My presentations
Click on DermpathJC
Here are the corresponding diagnoses to the online virtual images:
- Keratoacanthoma
- Verrucous carcinoma
- Micronodular basal cell carcinoma
- Morpheaform BCC
- Infiltrative bcc
- Bapoma
- Trichoblastic carcinoma
- Secretory carcinoma
- Endocrine mucin producing sweat gland carcinoma
- Signet ring/histicocytoid carcinoma
- Squamoid eccrine carcinoma
- CEA
- Adnexal adenocarcinoma NOS
- Leiyomyosarcoma
- Pseudomyogenic hemangioendothelioma
- Epithelioid histiocytoma
- Type E LYP
- Erdheim Chester Disease
- Conjunctival melanoma
- Conjunctival primary acquired melanosis
- Conjunctival nevus
Thanks to all who participated! See you in December! Save the date 12/27/2018, 9pmEST.
Kind regards,
Silvija Gottesman, MD