Mona Abdel-Halim

ABSTRACT: Crystalglobulinemia (CG) is a rare disorder characterized by crystallization of monoclonal immunoglobulins in the microcirculation leading to multiorgan vascular thrombosis and ischemic injury. The main cause of CG is multiple myeloma. We report a case of a 52-year-old man who presented with widespread necrotizing plaques and ulcerations. A skin biopsy revealed eosinophilic rectangular-shaped crystals occluding the lumina of blood vessels with no associated features of vasculitis. The crystals were Periodic acid-Schiff stain positive. The findings were diagnostic of CG. Extensive work up lead to the discovery of multiple myeloma. Awareness of CG is important because it may be the first presenting manifestation of an underlying serious hematological malignancy.

Hypopigmented interface T-cell dyscrasia (HITCD) is a distinct form of lymphoid dyscrasia that may progress to hypopigmented mycosis fungoides (HMF). We compared both diseases as regards their CD4/CD8 phenotype and expression of granzyme B and tumor necrosis factor-alpha (TNF-α) and how these are affected by narrow-band UVB (nb-UVB). The study included 11 patients with HITCD and 9 patients with HMF. They received nb-UVB thrice weekly until complete repigmentation or a maximum of 48 sessions. Pretreatment and posttreatment biopsies were stained using anti CD4, CD8, TNF-α, and granzyme B monoclonal antibodies. Epidermal lymphocytes were CD8 predominant in 54.5% and 66.7% of HITCD and HMF cases, respectively, whereas dermal lymphocytes were CD4 predominant in 63.6% and 66.7%, respectively. Significantly, more dermal infiltrate was encountered in HMF (P = 0.041). In both diseases, granzyme B was only expressed in the dermis, whereas TNF-α was expressed both in the epidermis and dermis. No difference existed as regards the number of sessions needed to achieve repigmentation or cumulative nb-UVB dose reached at end of study. (P > 0.05). Narrow-band UVB significantly reduced only the epidermal lymphocytes in both diseases (P ≤ 0.05) with their complete disappearance in 8 (72.7%) HITCD and 6 (66.7%) HMF cases. In both diseases, nb-UVB did not affect granzyme B or TNF-α expression (P > 0.05). In conclusion, both diseases share the same phenotype, with HITCD being a milder form of T-cell dysfunction. In both diseases, epidermal lymphocytes are mainly CD8-exhausted cells lacking cytotoxicity, whereas dermal cells are mostly reactive cells exerting antitumor cytotoxicity. Tumor necrosis factor-alpha mediates hypopigmentation in both diseases and prevents disease progression. Repigmentation after nb-UVB in both diseases occurs before and independently from disappearance of the dermal infiltrate.

BACKGROUND: The distinction of trichoepithelioma from basal cell carcinoma in small superficial biopsies is important but often challenging. This has inspired many scientists to test the validity of immunohistochemical markers in the differential diagnosis.

OBJECTIVES: To develop an immunohistochemical protocol that helps in differentiation between both trichoepithelioma (TE) and basal cell carcinoma (BCC) with higher sensitivity and specificity.

METHODS: Using standard immunohistochemical techniques, we examined 10 TEs and 19 BCCs for the expression of CK19, Ki-67, androgen receptors (AR), CD10, and PHLDA1.

RESULTS: Immunoreactivity of AR, Ki-67, and CD10 in tumor cells was significantly higher in BCC than TE with a diagnostic accuracy in BCC of 75.5%, 75.8%, and 79.3% respectively, whereas immunoreactivity of PHLDA1 in tumor cells and stromal CD10 was significantly higher in TE than BCC with a diagnostic accuracy in TE of 100% and 82.8%, respectively. In contrast, immunoreactivity for CK19 showed no statistically significant differences between both tumors.

CONCLUSION: The analysis of CD10, Ki-67, and PHLDA1 can be used as a helpful immunohistochemical panel in the distinction between TE and BCC especially in small and superficial biopsies.