Thursday, February 21, 9pm EST
Article discussed: Solid carcinoma is a variant of microcystic adnexal carcinoma: A 14‐case series
Authors: Yosmar Carolina, Perez-Gonzalez, Ramon Bosch-Princep, Maria-Teresa-Fernandez-Figueras, Arno Rutten.
Temporary open access at: https://onlinelibrary.wiley.com/doi/full/10.1111/cup.13351
Summary prepared by Abha Soni, DO, MPH (@AsoniDO)
Journal Club summary:
This month’s journal club discussed a rare skin neoplasm that closely resembles the solid areas of microcystic adnexal carcinoma (MAC). The article was a good review of the histologic, and immunohistochemical features of this entity.
In case you missed our discussion this week, the summary is provided below:
Only 16 cases of sold carcinoma have been previously published. This paper presents 14 additional cases of sold carcinoma and reviews their morphologic and immunohistochemical features.
- Groups of neoplastic epithelial cells with small monomorphous nuclei.
- Cells form small solid aggregates that vary in size and shape and fill the dermis and extend through adipose tissue.
- Nuclear atypia and mitotic figures are rare.
- Perineural invasion and infiltrative borders are identified.
- Small cornifying cysts/follicular derived cysts can be found in the upper part of the neoplasm.
- Some nests show clear cell features without a prominent basal cell layer.
- These cells showed abundant cytoplasm, single nucleolus, and their nuclei tended to be located near the apices of the cells
- Neoplastic cells exhibit high-molecular weight keratin (cytokeratin 5/6), broad specterum keratin (AE1/AE3), and p63, with focal CEA immunoreactivity.
- Negativity for ER, PR, BerEP4, EMA, Cytokeratin 7, Cytokeratin 20, Cytokeratin 18, SMA, S-100, CD15, and GCDFP-15.
- p53 is associated with uncontrolled proliferation and interpreted as an indicator of aggressive behavior and was only expressed in less than 5% of cells in the tested cases.
- p63 shows a homogenous expression than in classic MAC.
- CK19 is positive in some small ductal structures within the neoplasm
- PHLDA-1 was negative in the cases studied (unlike previous papers). It appeared to stain part of the epithelium of cystic structures.
- Clinicians must determine whether this is a unique clinicopathologic entity or if it belongs to the spectrum of MAC.
- Differential diagnosis includes:
- Clear-cell dermal duct tumor
- Differentiating features: Absence of cystic structures on the superficial aspect of the neoplasm in dermal duct tumor, and absence of infiltrative pattern without perineural invasion.
- Sclerosing basal cell carcinoma
- Differentiating features: BerEP4 would be positive in both sclerosing and clear cell BCC and negative in solid carcinoma/solid variant of MAC.
- Desmoplastic trichoepithelioma
- Tumor cells are basaloid and show presence of rims of collagen bundles around the neoplastic cell cords as well as absence of perineural involvement. Additionally, are confined to the upper/mid dermis.
- Solid variant of MAC vs classic MAC:
- Classic MAC clinically presents in locations such as lips and face and rarely the scalp. Whereas, the current series, scalp location seems to be more associated with the solid variant of MAC.
- Solid carcinoma should be referred to as the solid variant of MAC, histopathologic features of this entity belong to the MAC morphologic spectrum.
- Clear-cell dermal duct tumor
See you all next month! 😉