Diagnostic utility of plasmacytoid dendritic cells in dermatopathology.

Differentiating cutaneous diseases that mimic each other clinically and histopathologically can at times be a challenging task for the dermatopathologist. At the same time, differentiation of entities with overlapping features may be crucial for patient management. Although not seen in normal skin, plasmacytoid dendritic cells usually infiltrate the skin in several infectious, inflammatory/autoimmune and neoplastic entities. Plasmacytoid dendritic cells can be identified in tissue using specific markers such as CD123 and/or blood-derived dendritic cell antigen-2. Plasmacytoid dendritic cells are the most potent producers of type I interferons and their activity may therefore be assessed indirectly in tissue using human myxovirus resistance protein A, a surrogate marker for type I interferon production. In recent years, accumulating evidence has established the utility of evaluating for specific plasmacytoid dendritic cell-related parameters (plasmacytoid dendritic cell content, distribution and clustering and/ or human myxovirus resistance protein A expression) as a diagnostic tool in differentiating cutaneous diseases with overlapping features such as the alopecias, lupus and its mimics, and neoplastic entities. In this review, we provide an update on the current evidence on this topic and on the contexts where this can be a useful adjunct to reach the histopathological diagnosis.

Macular hypopigmentation, hair loss and follicular spongiosis: A distinct clinicopathological entity.

BACKGROUND: Hypopigmented macules are seen in a variety of disorders and the diagnosis rests on clinicopathological correlation. However, some cases are difficult to classify and pose a diagnostic challenge. AIM: To describe the clinical and histopathological features of patients with hypopigmented macules and follicular spongiosis on histopathology. MATERIALS AND METHODS: We undertook a retrospective analysis of clinical and histopathological findings in 12 patients who presented with clinically nondiagnostic hypopigmented macules and showed follicular spongiosis on skin biopsy, at All India Institute of Medical Sciences, New Delhi, India between January 2015 and October 2016. The findings were compared with 12 patients with "unclassified" hypopigmented macules, who did not show follicular spongiosis on skin biopsy. RESULTS: A total of 12 patients with hypopigmented macules showed spongiosis affecting the follicular epithelium on histopathology. There were eight men and four women, most in their second decade (mean age 19.1 ± 8.05 years), presenting with hypopigmented macules most commonly on the upper limbs, for a mean duration of 6.33 ± 5.10 months. Clinically evident lesional hair loss was seen in all patients, and follicular prominences in seven (58%) patients. Histological features suggestive of other diagnosis, namely leprosy, mycosis fungoides or sarcoidosis were not seen in any biopsy. Alcian blue stain revealed an minimal amount of mucin in one biopsy. Clinically apparent hair loss and follicular prominences were found to be statistically significantly associated with histological evidence of follicular spongiosis (P < 0.001 and 0.003, respectively). LIMITATIONS: Our study is limited by its retrospective design and small sample size. CONCLUSIONS: Patients with hypopigmented macules and follicular spongiosis on histopathology may represent a distinct clinicopathological entity that is associated with lesional hair loss and follicular prominences. It is probably a variant of an endogenous dermatitis similar to pityriasis alba.

Leprosy on the scalp

Abstract Leprosy is a chronic infectious disease caused by Mycobacterium leprae. This bacillus has a high predilection for skin and peripheral nerves. The scalp’s anatomical properties do not favor the development of such mycobacterium. We report a case of leprosy with scalp involvement, a rare occurrence in our literature.

Leprosy on the scalp.

Leprosy is a chronic infectious disease caused by Mycobacterium leprae. This bacillus has a high predilection for skin and peripheral nerves. The scalp's anatomical properties do not favor the development of such mycobacterium. We report a case of leprosy with scalp involvement, a rare occurrence in our literature.

Multicentric calcified trichilemmal cysts with alopecia universalis affecting siblings.

Trichilemmal cyst, also known as "pilar cyst," is a benign cyst containing keratin and its breakdown products with a wall resembling external root sheath of hair. It occurs mostly in females as a solitary firm nodule over scalp. Occurrence of multiple trichilemmal cysts in areas other than scalp is extremely rare. We are reporting a case of a 40-years-old female who presented with multiple calcified trichilemmal cysts in multicentric distribution associated with alopecia universalis. Similar complaints were present in elder sister of the patient, indicating a genetic background. Multicentric distribution of trichilemmal cysts, calcification, familial occurrence, and association with alopecia universalis seen in our case are all rare and intriguing features.

Psoriatic alopecia - fact or fiction? A clinicohistopathologic reappraisal.

BACKGROUND: The incidence of psoriatic alopecia in psoriatic patients is underwhelming, given the prevalence of psoriasis in the North American population. Recently, a 60-year-old Albanian female, lacking a significant medical history for psoriasis, presented to our clinic with a 1-year history of "dandruff" associated with itch, hair thinning, and histopathologic evidence consistent with prior reports of "psoriatic alopecia." AIMS: The absence of preceding or concomitant psoriasis suggests that the patient's alopecia is an antecedent manifestation of psoriasis, thus prompting this retrospective study to ascertain better the relationship between alopecia and psoriasis. METHODS: We performed a retrospective review of 33 scalp biopsies on 31 patients having histopathologic diagnosis of psoriasis belonging to 31 patients seen between 2007 and 2010. RESULTS: Alopecia was a presenting feature in 48% of cases with definitive clinical and/or histopathologic diagnosis of psoriasis (scale crust with neutrophils, psoriasiform epidermal hyperplasia, and hypogranulosis). The most common follicular-related changes were infundibular dilatation (87%) followed by perifollicular fibrosis (77%), perifollicular lymphocytic inflammation (68%), thinning of the follicular infundibulum (55%), and fibrous tracts (28%). Of interest, sebaceous glands were absent in 60% and atrophic in 25% of cases. CONCLUSION: While a major limitation of this study is that it is a retrospective one, given that these changes are common to varying degrees in all lymphocytic scarring alopecias, we posit that psoriatic alopecia likely represents a secondary clinical change to a primary process and is not a unique histopathologic entity. A prospective study with a control group that includes lymphocytic scarring alopecias from non-psoriatic patients is required to support our findings.

Hutchinson-Gilford progeria syndrome.

Progeria is a rare genetic disorder characterized by premature aging, involving the skin, bones, heart, and blood vessels. We report a 4-year-old boy who presented with clinical manifestations of progeria. He had characteristic facies, prominent eyes, scalp and leg veins, senile look, loss of scalp hair, eyebrows and eyelashes, stunted growth, and sclerodermatous changes. The present case is reported due to its rarity.