Mucha-Habermann disease vs. Secondary syphilis

Differential Diagnosis

Mucha-Habermann disease Secondary syphilis 1. Superficial and deep perivascular infiltrate in wedge-shaped configuration 1. No wedge shape of the superficial and deep perivascular infiltrate 2. Lymphocytes predominant in the dermal infiltrate 2. Histiocytes or plasma cells predominant in the dermal infiltrate 3. No multinucleate histiocytes 3. Multinucleate histiocytes sometimes 4. No plasma cells 4. Plasma cells nearly always 5. No thick-walled blood vessels 5. Thick-walled blood vessels lined by plump endothelial cells 6. Little, if any, psoriasiform acanthosis 6. Psoriasiform acanthosis common 7. Rete ridges may be effaced 7. Rete ridges usually preserved 8. Both spongiosis and ballooning often 8. No spongiosis or ballooning as a rule 9. Intraepidermal, and even subepidermal, vesicles in some lesions 9. No vesicles as a rule 10. No spongiform pustules 10. Spongiform pustules in the rupial expression especially 11. Scattered necrotic keratocytes, often numerous, in the epidermis and the upper part of adnexal epithelium 11. No necrotic keratocytes usually 12. Confluent epidermal necrosis and ulceration in some lesions 12. No confluent epidermal necrosis in ulceration, except in lues maligna 13. Scale-crusts containing neutrophils beneath the remnant of an original normal cornified layer 13. No remnant of a normal cornified layer

Discussion

Distinction histopathologic between Mucha-Habermann disease and secondary syphilis may be difficult because the two diseases have so many attributes in common. Both may be associated with a superficial and deep perivascular and lichenoid infiltrate of mononuclear cells, acanthosis, parakeratosis, and erosion or ulceration. Erythrocytes are extravasated in the dermis, neutrophils and lymphocytes may be seen in the epidermis, and neutrophils may be trapped in parakeratotic scale-crusts. Edema of the papillary dermis and pallor of the viable epidermis are other changes shared often.

Most of the findings that enable differentiation of Mucha-Habermann disease from secondary syphilis are a reflection of the pace of development of the respective processes pathologic. Mucha-Habermann disease erupts as papules and vesicles; secondary syphilis evolves much more slowly as papules and, in adults, never as vesicles. Spongiosis (intercellular edema) and ballooning (intracellular edema) are met with commonly in Mucha-Habermann disease, but not in secondary syphilis. Scattered, individual necrotic keratocytes and even confluent necrosis of the epidermis are findings expected in Mucha-Habermann disease, but rarely are they encountered in secondary syphilis (except as a consequence of a vasculitic expression of that disease termed "lues maligna"). Acanthosis, a sign usually of a process evolving slowly, if present at all in Mucha-Habermann disease, hardly ever is marked, whereas prominent proliferation of keratocytes in psoriasiform pattern is common in secondary syphilis.

The infiltrate of inflammatory cells in Mucha-Habermann disease, from beginning to end of it, is made up almost entirely of lymphocytes; histiocytes are not present and, therefore, granulomas do not come into being. In contrast, secondary syphilis, except for the earliest phase of it, practically never is constituted almost entirely of lymphocytes; plasma cells or histiocytes predominate and granulomas form commonly as lesions progress. Differences in character of infiltrates are crucial for distinguishing between the two diseases, whose overall architectural pattern often is so similar, but whose nature fundamental is so different.

Clinically, both Mucha-Habermann disease and secondary syphilis present themselves usually as widespread papules that, in time, disappear without treatment. The polymorphous eruption of Mucha-Habermann disease typically affects the trunk, axillae, and extremities, palms and soles rarely being involved. Oral mucosa and genital mucosa hardly ever are caught up in the process, and nearly always, the face is spared. Lesions are observed concurrently at all stages of development of them; new papules appear as old ones resolve. The lesions various of a Mucha-Habermann disease include macules, papules surmountd by brawny scale (pityriasis), flat-topped papules (lichenoides), smooth-surfaced, purpuric, necrotic, or ulcerated papules, vesicles, and scars (varioliformis). The disease has a predilection for adolescents and young adults, but children and older persons may be affected by it, too. In most patients, the condition lasts for weeks, but in some it takes a more protracted course. When longstanding, i.e., for many months and even years, lesions tend to consist wholly of variably red papules with fine scales. That prolonged form of the disease in which individual lesions evolve more slowly is known as "pityriasis lichenoides chronica." The acute form of Mucha-Habermann disease, clinically and histopathologically, is a caricature of the chronic form, the lesions racing to apogee in hours sometimes, rather than in weeks. A fulminant, volcanic expression of Mucha-Habermann disease represents a great exaggeration of the acute form.

Secondary syphilis also is polymorphic clinically, but all of the lesions in the skin and on mucous membranes are variations of papules. The papules are distributed symmetrically and have a dull red appearance that in Caucasian skin has been compared to the color of ham. The papules tend neither to vesiculate nor ulcerate, except for those of lues maligna. They are inclined to be distributed widely and almost always involve palms and soles. Lesions heal without scarring and do not recur unless a patient either is treated inadequately or is reinfected. White patches may occur on the oral mucosa and condyloma lata on genitalia. A patchy "moth-eaten" alopecia may result from infiltrates of mononuclear cells in peri-infundabular and perifollicular array.

In cases suspected of being secondary syphilis, demonstration of the causative spirochete, Treponema pallidum, confirms the diagnosis. Various silver stains have been employed to demonstrate spirochetes mainly in the epidermis and occasionally around the vessels of the superficial plexus. When in secondary syphilis many neutrophils are present in an epidermis, sections stained by silver are seen to teem with spirochetes. With the advent of immunoperoxidase techniques, sensitivity for detection of spirochetes has increased so greatly that in almost 90% of specimens from lesions of early secondary syphilis causative organisms can be revealed strikingly.

Neither Mucha-Habermann disease nor secondary syphilis is accompanied by true vasculitis as a rule; neither fibrin in the wall of venules nor a thrombus in the lumen of them can be discovered in most lesions. In a rare instance, leukocytoclastic vasculitis may occur in established papules of secondary syphilis (lues maligna). Equally rarely, "lymphocytic vasculitis" may be observed in Mucha-Habermann disease, it always being an epiphenomenon.

Ref:

Differential Diagnosis In Dermatopathology I, Ii, Iii, Iv.chm