Dermpedia

Sharing dermatology and dermatopathology knowledge

This lesion showed a positive pseudo-Darier sign (which is a transient piloerection and elevation of a lesion induced by rubbing and is observed especially in congenital smooth muscle hamartomas)

Immunohistochemical staining for α-SMA was positive in the tumor cells.

pending

Halo nevi are so called because they clinically surrounded surrounded by a white halo.  They tend to occur in children and younger adults and, as in this case, are most common on the trunk.

Histologically, one sees a dense lichenoid infiltrate of lymphocytes and histiocytes, which may obscure the nevus cell nests, potentially causing them to be missed if they are not carefully sought.  Immunohistochemical stains may aid in their detection.

Halo nevi may be junctional, compound or dermal.

Pilomatrixoma presents as a slow growing, firm to hard nodule (0.5- 3 cm) appearing, in decreasing frequency, on the head (cheek most common), upper limbs, neck, trunk, lower limbs.

Its pathogenesis is associated with the Wnt/wingless signal transduction pathway and mutated B-catenin protein, which plays a structural role in cell-cell formation between adherens junctions and the actin cytoskeleton.

There have been rare reports of pilomatrix carcinoma arising out of benign pilomatrixomas, and sites treated for pilomatricoma.

Who is affected: young (<20 years old, many before10 years old) with second peak in 6-7th decades of life.

Treatment: surgery is curative. Local recurrence in 2-3% of cases.

Microscopic features: 

- Lobules of basaloid and ghost cells (biphasic cell population

- Early lesions show brisk mitoses (indicating rapid growth and not a malignancy) and sheets of germinative basaloid cells with uniform nuclei and small nucleoli.

- As cells mature, they become larger with abundant eosinophilic cytoplasm, and pyknotic nuclei

- Melanin pigment in basaloid and tumor cells

- Foreign body giant cell reaction common

- Calcification, granular and basophilic, may be seen

- Atypical features in the elderly such as basloid cell pleomorphism, loss of polarity, nuclear hyperchromatism, and marked mitotic activity.

Differential diagnosis: infundibular cysts, trichoepithelioma.

2 punch biopsies were performed. Both vertical and horizontal sections were evaluated.

Venous lakes are fairly common vascular ectasias presenting on sun damaged skin of the elderly, showing a predilection for the lip.

Lesions may be multiple and measure up to 1 cm in diameter.

The pathogenesis may be due to possible defective stromal support.

Microscopic features: dilated and congested veins in the superficial dermis.  No evidence of vascular proliferation.  

Scabies is a highly contagious dermatogical condition caused by the mite, Sarcoptes scabiei. The female mite burrows into the epidermis to lay eggs. Larvae hatch in 3-5 days, mature about 2 weeks later, and then migrate to the surface and mate to continue the cycle. Papules and burrows are often found in the webbing between the fingers and toes, or the sides of fingers.

The host immunologic response (immune complex mediated)  to the mite or its feces (seen microscopically as scybala when hardened) produces the intense itching experienced by patients. Secondary infection is common. 

Scabies transmitted by prolonged skin to skin contact contact.

Who is affected: those living in poor socioeconomic conditions, overcrowded areas (eg nursing homes, jails), and have poor personal hygiene. Scabies can be transmitted during sexual contact.

Microscopic features: acanthosis, hyperkeratosis, and often spongiosis with lymphocytic infiltrate.  The mite is usually subcorneal, at the junction between the epidermis and stratum corneum.

Diagnosis: is made by visualizing the mite, mite parts or its feces.

Treatment of choice: topical permethrin cream.

Prevention measures: good personal hygiene; machine wash infected laundry with hot water; seal infected objects (toys) in a plastic bag for 3 days.

Key features include the small cells of the melanocytes and their nuclei (similar in appearance to the overlying conjunctival epithelial cells) and the highly characteristic induction of cysts formed by the conjunctival epithelial cells.  The S-100 stain confirms the melanocytic nature of the lesion.

Trichofolliculoma is a rare pilar tumor which typically presents on the head or neck.  Histologically, it shows one to several dilated hair follicles usually containing keratin, from which numerous small follicles branch off.

As in this case, focal areas of sebaceous differentiation may be seen within the follicles (the vacuolated cells seen at high power).  Sebaceous elements are more common in late-stage trichofolliculomas.  A variant termed "sebaceous trichofolliculoma" has also been described.  This designation should be reserved for cases in which large sebaceous follicles connect to a central cavity.

Nevi of acral skin (aka MANIAC: melanocytic nevus with intraepidermal ascent of cells) tend to be small macular or slightly elevated lesions.  Histologically, they are junctional nevi whose distinguishing feature is their characteristic upward migration of melanocytes into the epidermis.

This case displays neoplastic melanocytes extending upward into the stratum corneum.  The relatviely severe melanocytic atypia and irregularity of the nests warrant a diagnosis of atypical acral nevus.  The degree of atypia, however, falls short of that required for a diagnosis of acral lentiginous melanoma, the principal entity that must be excluded.  Additional features which are characteristic of acral melanoma are contiguous basilar proliferation and more pronounced pegetoid spread.

Pretibial myxedema is an infiltrative dermopathy and rare complication of Graves disease (incidence 1-4% of patients).

Clinical symptoms: 

• limited to anterior aspect of lower extremities and dorsa of feet, rarely other location
• waxy (pink, yellow) induration of the skin or non pitting edema
• orange peel (peau d'orange) skin, sometimed nodules

Biopsy reveals mucin deposition in the mid to lower dermis, confirmed by Alcian blue and collagen stains. There is no increase in fibroblasts.

This is a classic example of this entity.

It is a precursor of mucinous carcinoma of the eyelid. 

This is a very early patch stage lesion. Key diagnostic features include:

• dissecting capillaries
• inflammation with plasma cells
• focal red cell extravasation of blood cell with hemosiderin deposition