Michael P. Lee, MD

For anyone intubating C19 patients, a Atlanta local acrylic case company has made these protective shields free to hospitals.

Message me if interested.

Sorry for the recent lack of posts. Be back at it soon.

Cutaneous lymphadenoma - currently believed to be variant of trichoblastoma - is a benign tumor most commonly on the head and neck of older individuals. They are typically biopsied to rule out BCC and other common malignancies.

These tumor are similar to other variants/derivatives of trichoblastoma, complete with CK20+ Merkel cells within tumor islands. Similar to trichoepitheliomas, the periphery of the tumor islands are positive for BCL2, differentiating it from BCC (diffuse staining of tumor).

The prior belief that these lesions were derived from pilosebaceous and sweat glands are fair assumptions since many of the tumor islands may show ductal like epithelium as well as sebocyte like cells.

Microscopically:
1. Dermal tumor composed of pale staining islands with dark blue rim, not dissimilar from clear cell BCC from low power.
2. Embedded in dense fibrous stroma.
3. Tumor cells show large nuclei with vesicular (translucent due to peripheral dispersion of chromatin) chromatin and prominent nucleoli. No mitotic figures.
4. Admixed with lymphocytes T>B
5. Basaloid rim of cells without clefting
6. Ductal like structures are negative for CEA but positive for EMA.

New video on Cutaneous Lymphadenoma. Great job everyone for making the diagnosis. For those interested, there's a lymphoepithelial like carcinoma at end for comparison.

Cutaneous Lymphadenoma with extras. Explained by a dermatopathologist. Unk #17. #Boardsready Cutaneous lymphadenoma - currently believed to be variant of trichoblastoma - is a benign tumor most commonly on the head and neck of older individuals. They...

Scary cells don’t always imply bad behavior.

This is an Atypical fibroxanthoma (AFX), a tumor that develops on the sun damaged skin of older people. While it is often rapidly growing, has bizarre multinucleated and pleomorphic cells with numerous mitotic figures, it is generally well circumscribed and removal of the lesion is typically curative (rare to recur or metastasize).

*Caveat* if tumor extends deeply into subcutis or invades other structures, consider undifferentiated pleomorphic sarcoma, which can be histopathologically and immunohistochemically indistinguishable (in fact, some consider AFX as a superficial variant of UPS).

New vid on Sweet's disease. unknown 16.

Sweet’s disease. If you eat too many SWEET CHERRY RED (color of the lesions) jolly ranchers, you may get a fever. This is Sweet's syndrome (aka acute febrile neutrophilic der...

This is Sweet's syndrome (aka acute febrile neutrophilic dermatosis) - a somewhat uncommon lesion that typically presents after a URI. These lesions are red, hot, and quite tender. Patient's typically have an associated fever. The skin lesions are characteristically red and often lifted.

Sweets is an autoinflammatory neutrophilic dermatosis when one's own immune system damages tissue. There is also an association with other autoinflammatory conditions like rheumatoid arthritis, Lupus, as well as HLA B54.

Microscopically:
1. Neutrophils often diffusely through dermis
2. Massive subepidermal edema causing lifting of the skin
3. Fragmentation of the neutrophils (karyorrhexis)
4. Red cell extravasation
5. Occasional vasculitis (LCV)

New vid on Trichofolliculoma up now on youtube

Trichofolliculoma - momma and her babies Unk 15 #leeunknowns #dempathmadeEZ Momma and her babies! This is a trichofolliculoma, a benign follicular hamartoma most common on the head and neck. The presence of multiple hairs emptying th...

Momma and her babies!

This is a trichofolliculoma, a benign follicular hamartoma most common on the head and neck. The presence of multiple hairs emptying the cystically dilated pore is a clinically useful diagnostic clue.

Microscopically:
1. Cystically dilated large diameter hair follicle (momma)
2. Numerous smaller hair follicles (babies) radially distributed around the momma hair follicle
3. Smaller hair follicles form hairs that can usually be seen within the cystic momma hair follicle
4. In older lesions, the smaller hair follicles will evolve and form sebaceous glands. Many people consider this morphologically identical to folliculosebaceous cystic hamartoma (stroma may be different).

This is what scabies infestation looks like under a microscope. These mites like to form little channels/burrows just under the top layer of the skin and continue to dig and cause people to go crazy over the intense itch 😩. The itch probably results from an allergic reaction to the organisms waste (f***s). The good news is, it's treatable with medication that can be prescribed to you by your doctor.

This lesion is called a mixed tumor aka Chondroid Syringoma. Mixed because it has variable amounts of chondroid (cartilaginous matrix) and syringoma (benign sweat duct tumor). These are entirely benign lesions. These tumors are formed from the same glands and ducts that produces sweat when exercising.

Many things in dermpath are instant pattern recognition - this entity being a great example of that. Cartilage like material (star) + sweat duct epithelium (arrow) = mixed tumor / chondroid syringoma.

“Doc help me, I have ringworm all over my body and it’s driving me nuts”

This is Mycosis Fungoides (MF) - a type of cancer of the cells that are supposed to protect our bodies from infection - the lymphocyte.

MF is a fairly rare T-cell lymphoma (cancer) which can look like a scaly, itchy rash, not too dissimilar from eczema or a fungal infection initially. It usually involves non sun-exposed skin, the so-called bathing suit distribution or double covered areas of the trunk.

Most people with early-stage disease will essentially live a normal life span with treatment. However, in some cases, these eczema or ringworm like lesions may evolve into fungating mushroom-like masses and nodules and can even spread outside of the skin to lymph nodes and other systems.

Diagnostic keys:

1. Psoriasis-like thickening of the skin (psoriasiform)
2. Dense band-like lymphocytic inflammation (lichenoid)
3. Dark-blue and distorted appearing lymphocytes which form ->
4. Small collections within the epidermis as well as ->
5. Lining up at the dermoepidermal junction.
6. Wiry fibrosis of the upper dermis
7. Paradoxical amount of intercellular edema (spongiosis) given the amount of inflammation within the epidermis.
8. Lack of other inflammatory cell types
etc..

Check out my new video on Angiolymphoid hyperplasia with eosinophilia (epithelioid hemangioma)

Angiolymphoid hyperplasia with eosinophilia (epithelioid hemangioma) explained by a dermpath Angiolymphoid hyperplasia with eosinophilia (epithelioid hemangioma) angio (blood vessel) lymphoid (immune cells) hyperplasia (growth) with eosinophilia ALHE...

Angiolymphoid hyperplasia with eosinophilia (epithelioid hemangioma) angio (blood vessel) lymphoid (immune cells) hyperplasia (growth) with eosinophilia

ALHE is a benign vascular disorder that most commonly presents as a painless, pink to red, single to multiple, nodules to plaques. They are commonly on the head and neck and 30-40 (😊 blooming adults) is usually when they start showing up.

Microscopic diagnostic keys:
1. Dermal proliferation of blood vessels with inflammation.
2. Usually a central thick-walled vessels and smaller vessels around the edge
3. Vessels are lined by plump endothelial cells with histiocytoid vesicular chromatin.
4. Admixture of lymphocytes, histiocytes, and eosinophils.

Ants and earthworms aren’t the only things in the soil.

Phaeohyphomycosis is a term used to describe a large and diverse group of pigmented molds /fungal infections in the skin. These organisms have hyphae and yeast forms. Chromomycosis lack hyphae forms. Culture is necessary for speciation.

In general, the localized forms are found in individuals with an intact immune system while systemic infections are in immunocompromised. The appearance of the lesions can range from nodules to cystic and occasionally wart or squamous cell carcinoma-like.

The organisms are found in wood, soil, and vegetation and are typically introduced into the skin by a splinter or other traumatic inoculation.

Characteristic microscopic findings:

1. Cavity or cyst surrounded by mixed inflammation with giant cells, histiocytes, and neutrophils.
2. Brown filamentous, thick-walled hyphae and yeasts with bubbly cytoplasm.
3. Differs from chromomycosis which are round spherical organisms that undergo internal septation

New video on dematiaceous fungi up now.

Dematiaceous fungi - phaeohyphomycosis and chromomycosis unknown 13 Ants and earthworms aren’t the only things in the soil. Phaeohyphomycosis is a term used to describe a large and diverse group of pigmented molds /fungal inf...

This is a disease that was once associated with significant social stigma, frequently causing the individual to be ostracized to so called "colonies", where those afflicted were doomed to deformity with fingers and toes falling off. **an effected individual as depicted in Braveheart** ——————————————————————————-Can you guess the disease?

Leprosy. Contrary to what was once believed, this is not highly contagious, and it is easily treated with a combination of antibiotics. Leprosy still exists today. The armadillo is a known carrier. ———————————————————————————
It is caused by a bacteria called Mycobacterium leprae, a organism similar to that which causes tuberculosis. Under the microscope, we see (in some variants) granulatomous inflammation - the pale pink sausage like structures labeled arrow - and chronic inflammation (blue dots everywhere). Inflammation causes nerve damage which contributes to the deformities. Nerve damage --> can't feel that i just stepped on a nail --> infection -->deformity. ———————————————————————————-It still exists today in some parts of the world, including the United States. A recent case was associated with some kids using the carcass of an armadillo as tee- ball practice. I guess the armadillo got the last laugh. 😂

New video up. Pretibial myxedema. Unknown #12

Pretibial (localized) myxedema explained by a dermatopathologist unknown #12 #dermpathiseasy Pretibial myxedema. This is associated with hyperthyroidism (the opposite of hypothyroidism which has received much attention recently), and is one of the ch...

Pretibial myxedema.

This is associated with hyperthyroidism (the opposite of hypothyroidism which has received much attention recently), and is one of the charactersitic symptoms of Grave's disease (autoimmune hyperthyroidism). Other symptoms of Grave's include goiter (enlargement of thyroid), exophthalmos (eyes bulging) and clubbing of the digits, amongst others.

Microscopically, there is often hyperkeratosis (star- thick, scaly), follicular plugging and the skin can become bumpy (papillomatosis) and verruciform. There is extensive mucin deposits in the dermis (orange arrow), which splays apart collagen fibers (the pink strands). On high power, you may be able to see the mucin droplets. They look like beads on a string.

Spot Dx unknown 12. Bilateral shins, 42 yo F. Answer and video tomorrow.

Awesome compilation by Dr Johanna Baran Moore

Sometimes material is deposited into the skin, causing a rash or lesion. When it gets biopsied, unique patterns are observed under the microscope.

New video on poroma. Feedback appreciated. Thanks

Eccrine Poroma (acrospiroma) explained by a dermatopathologist unknown 11. This is a benign sweat duct tumor, in this case, a poroma (por - duct, oma - tumor). Acrospiroma = Benign Sweat Duct Tumor: Benign sweat duct tumors are deri...