Man with groin rash that won’t go away. What is your diagnosis? Crutchfield Dermatology Case of the Month.

A 64 year old man presented with a diagnosis of tinea cruris. He said that he had been treating it for 3 years without resolution. He reported using at least 3 different prescription anti-fungal creams and for the past 5 months and used a different prescription cream called triamcinolone. He reports little to no pruritus. With the rash being so resistant, his primary care doctor referred him to a dermatologist for evaluation.

Here is the clinical presentation:

I performed a a biopsy and here is what the resultant dermatopathology:
(I ordered recuts from the pathologist and took this picture through the ocular of my microscope, using my cell phone!)

What’s your diagnosis?

EXTRAMAMMARY PAGET’S DISEASE

DEFINITION    Extramammary Paget’s disease is an apocrine carcinoma that begins within the epidermis and presents itself clinically as a patch or a subtle plaque that extends centrifugally for many years before becoming a readily discernible thick plaque, a finding that signifies involvement by the carcinoma of the dermis, too.

COURSE    Extramammary Paget’s disease usually presents itself as a macule on genital skin and, less commonly, in the axilla.  In time, the macule becomes slightly scaly and even crusted.  Because Extramammary Paget’s disease is a malignant neoplasm, i.e., an apocrine carcinoma that begins with a proliferation of individual neoplastic cells within the epidermis, it grows slowly, but irrepressibly.  A scaly macule becomes a scaly patch and, in time, the epidermis thickens as a consequence of the proliferation of Paget cells (cells of apocrine carcinoma).  The patch may become a subtle plaque that then expands slowly to achieve a size of many centimeters.
As a rule, the neoplastic cells of extramammary Paget’s disease remain in situ, i.e., confined to epidermal and adnexal (follicular, eccrine ductal, and apocrine ductal) epithelium for the lifetime of a person who has the disease.  As long as the cells of the apocrine carcinoma remain confined to epidermal and adnexal epithelium, the neoplastic process is biologically benign.  Only uncommonly do neoplastic cells of extramammary Paget’s disease descend into the dermis, and then only after many years, where they also then to grow slowly.  Nonetheless, metastases from the primary apocrine carcinoma in the skin may appear in regional lymph nodes and beyond them.  Patients have died from the effects of metastases of the extramammary Paget’s disease.

INTEGRATION: UNIFYING CONCEPT    Extramammary Paget’s disease is very different from mammary Paget’s disease, although both of them are apocrine carcinomas.  Paget’s disease is a primary cutaneous apocrine carcinoma that begins within the epidermis and extends from it directly into epithelial structures of adnexa.  Only uncommonly does it involve the dermis and rarely does it metastasize.  In contrast, mammary Paget’s disease is a primary apocrine carcinoma of the breast that begins in mammary glands, whence neoplastic cells ascend by way of lactiferous ducts to the epidermis.  Not uncommonly, neoplastic cells of mammary Paget’s disease extend from epidermal, mammary glandular, and lactiferous ductal epithelium into the dermis, from whence, not uncommonly, they metastasize.  Like other forms of metastasizing breast carcinoma, the malignant neoplastic process of mammary Paget’s disease all too often is fatal.  Parenthetically, signet-ring cells replete with mucin are found in the extramammary Paget’s disease, but nit in mammary Paget’s disease.
Despite the fact that the two conditions have in common the words “mammary” and Paget’s, “ extramammary Paget’s disease and mammary Paget’s disease, apocrine carcinomas both, are different neoplastic  processes.

THERAPY    Surgical excision with special attention being paid to margins at the periphery to ensure that the carcinoma has been removed completely. Surgical excision can be challenging and recurrence is not uncommon.

Reference
A CLINICAL ATLAS OF 101 COMMON SKIN DISEASES
With Histopathologic Correlation
A. BERNARD ACKERMAN, HELMET KERL, JORGE SANCHEZ, YING GUO, ANGELIKA HOFER, PAUL KELLY, TETSU KIMURA, GIOVANNI BORRONI, CHARLES CRUTCHFIELD, VOLKER STEINKRAUS, WOLFGANG WEYERS

A 64 year old man presented with a diagnosis of…